¹ On the influence of housing law for the development of family law see Barlow, A, Family Law and Housing Law: A Symbiotic Relationship?’ in Probert, R (ed), Family Life and the Law (Ashgate 2007) 11–27Google Scholar.

² For a history of cohabitation and the current situation in the US see Pleck, E, Not Just Roommates (University of Chicago Press 2012)CrossRefGoogle Scholar; for statistical material about European countries see Nazio, T, Cohabitation, Family and Society (Routledge 2008) 17–18CrossRefGoogle Scholar; for Australia see Healy, J, Marriage and Cohabitation: Issues in Society (Spinney 2010)Google Scholar and for Canada see Wu, Z, Cohabitation (OUP Canada 2000)Google Scholar.

³ Institute du Marriage et de la Familie Canada, <http://www.imfcanada.org/fact-sheet/canadian-cohabitation> accessed 14 February 2013. See for an explanation Laplante, B, ‘The Rise of Cohabitation in Quebec: Power of Religion and Power over Religion’ (2006) 31 Canadian Journal of Sociology 1Google Scholar; see also the discussion in Quebec (Attorney General) v A 2013 SCC 5 at [125–34].

⁴ Statistisches Bundesamt, Statistisches Jahrbuch 2011, Table 2.16, <https://www.destatis.de/DE/Publikationen/StatistischesJahrbuch/Bevoelkerung.pdf?__blob=publicationFile> accessed 14 February 2013.

⁵ Fairbairn, C, ‘“Common law marriage” and Cohabitation’ (Library House of Commons, Home Affairs Section 2012) 3Google Scholar. <http://www.parliament.uk/briefing-papers/SN03372> accessed 14 February 2013.

⁶ There is no space to do justice to the academic writing on the subject, but see Barlow, A and James, G, ‘Regulating Marriage and Cohabitation in 21st Century Britain’ 2004 MLR 143–67CrossRefGoogle Scholar; Scherpe, JM and Yassari, N, Die Rechtsstellung nichtehelicher Lebensgemeinschaften: The Legal Status of Cohabitants (Mohr Siebeck 2005)Google Scholar; Dethloff, N, ‘Gutachten A für den 67. Deutschen Juristentag’ Deutscher Juristentag, Verhandlungen des 67. Deutschen Juristentages Erfurt 2008 (CH Beck 2008) vol 1Google Scholar; Leckey, R, ‘Cohabitation and Comparative Method’ (2009) 72 MLR 48–72.CrossRefGoogle Scholar

⁷ See a list Quebec (Attorney General) v A 2013 SCC 5 at [280].

⁸ 2013 SCC 5.

⁹ The Miscellaneous Statutes (Domestic Relations) Amendment Act, 2001 (No. 2), SS 2001, c 51; Common Law Partners' Property and Related Amendments Act, SM 2002, c 48.

¹⁰ Law Commission, ‘Cohabitation: The Financial Consequences of Relationship Breakdown (2007) (LC307) <http://lawcommission.justice.govuk/docs/lc307_Cohabitation.pdf> accessed 13 February 2013.

¹¹ <http://www.publications.parliament.uk/pa/ld201011/ldhansrd/text/110906-wms0001.htm> accessed 7 June 2012; see the Supreme Courts' comments in Gow v Grant [2012] UKSC 29 at [44–56].

¹² For different financial arrangements used in relationships (which, however, only rarely seem to have been chosen consciously) see Burgoyne, C and Sonnenberg, S, ‘Financial Practices in Cohabitating Heterosexual Couples’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009) 89, 95–100Google Scholar.

¹³ Douglas, G, Pearce, J and Woodward, H, ‘Money Property, Cohabitation and Separation’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009) 139, 142–7Google Scholar.

¹⁴ Dauner-Lieb, B, ‘Die höchstrichterliche Rechtsprechung zur Ehegatteninnengesellschaft – offene Fragen zum Verhältnis von Güterrecht und Gesellschaftsrecht’ (2009) Familie und Recht 361, 363Google Scholar.

¹⁵ [1995] 4 All ER 562, 575.

¹⁶ B Dauner-Lieb (n 14) 361, 364; Hepting, R, Ehevereinbarungen (CH Beck 1984) 200–26Google Scholar.

¹⁷ Herring, J, Family Law (5th edn, Pearson Longman 2011) 200–4Google Scholar.

¹⁸ For a comparison of German and English law see Sanders, A, ‘Vermögensausgleich bei Solidargemeinschaften: Trust, (Ehegatten) Innengesellschaft und Bereicherungsrecht in Deutschland und England’ (2011) Zeitschrift für Europäisches Privatrecht 65–92Google Scholar.

¹⁹ Zweigert, K and Kötz, H, An Introduction to Comparative Law (trans Weir, T) (3rd edn, OUP 1998) 34–5Google Scholar, 44.

²⁰ Leckey (n 6) 48–72; Hyland, R, Gifts: A Study in Comparative Law (OUP 2009) 63–125CrossRefGoogle Scholar; Michaels, R, ‘Functional Method’ in Reimann, M and Zimmermann, R (eds), The Oxford Handbook of Comparative Law (OUP 2006) 339–83Google Scholar.

²¹ Apart from Quebec.

²² Sparkes, P, ‘How Beneficial Interests Stack up’ (2011) Conveyancer 156–63Google Scholar.

²³ The regime applies to both married as well as cohabiting couples. It has however, more practical importance for cohabitants as there is no statutory regime for cohabitants like the Matrimonial Causes Act 1973 that allows judges to redistribute property on divorce, see Stack v Dowden [2007] UKHL 17 at [43, 100].

²⁴ See CPS v Piper [2011] EWHC 3570.

²⁵ Crisp v Mullings [1976] 2 EGLR 103; Marsh v von Sternberg [1986] 1 FLR.

²⁶ Dyer v Dyer (1788) 2 Cox Eq 92; see on resulting trust Swadling, W, ‘Explaining Resulting Trusts (2008) 124 LQR 72–102Google Scholar.

²⁷ [1970] AC 777.

²⁸ [1971] AC 886.

²⁹ The trust is referred to as constructive rather than express because of the formality requirement in section 53(1)(b) LPA 1925 and the exception in section 53(2); Swadling, W, ‘The Fiction of the Constructive Trust’ (2011) 64 Current Legal Problems 399CrossRefGoogle Scholar.

³⁰ Grant v Edwards [1986] Ch 638; Eves v Eves [1975] 1 WLR 1338.

³¹ Burns v Burns [1984] 2 WLR 582; critical Flynn, L and Lawson, A, ‘Gender, Sexuality and the Doctrine of Detrimental Reliance’ (1995) 3 Feminist Legal Studies 105–21CrossRefGoogle Scholar.

³² [1991] 1 AC 107.

³³ Hammond v Mitchell [1991] 1 WLR 1127.

³⁴ Lloyds Bank v Rosset [1991] 1 AC 107, 132–3; see also Arden LJ analysis of Oxley v Hiscock in Lightfoot v Lightfoot-Brown [2005] EWCA Civ 201 at [27].

³⁵ Oxley v Hiscock [2004] 3 All ER 703, [69]; see also Midland Bank v Cooke [1995] 4 All ER 562; Springette v Defoe (1992) 24 HLR 552; Goodman v Gallant [1986] 2 WLR 236.

³⁶ [2007] UKHL 17; see Abbott v Abbott [2007] UKPC 53.

³⁷ See also Walker v Hall [1984] FLR 126; Springette v Defoe [1992] 2 FLR 388; Huntingford v Hobbs [1993] 1 FLR 736.

³⁸ Stack v Dowden [2007] UKHL 17 at [68] per Baroness Hale.

³⁹ ibid [56–70, esp. 60] per Baroness Hale and at 31 per Lord Walker.

⁴⁰ ibid [69].

⁴¹ ibid [60]; Gardner, S, ‘Family Property Today’ (2008) 124 LQR 422, 424Google Scholar; Douglas, Pearce and Woodward (n 13) 139, doubt that the factors chosen by her Ladyship are helpful.

⁴² Stack v Dowden [2007] UKHL 17 at [125].

⁴³ Cautiously approving Gray, K and Gray, S, Land Law (6th edn, OUP 2009)Google Scholar 7-072; Hopkins, N, ‘Regulating Trusts of the Home: Private Law and Social Policy’ (2009) 125 LQR 310, 336–7Google Scholar.

⁴⁴ Dixon, M, ‘The Never-Ending Story: Co-Ownership after Stack v Dowden’ (2007) 71 Conveyancer 456–61Google Scholar; Piska, N, ‘Intention, Fairness and the Presumption of Resulting Trust after Stack v Dowden’ (2008) MLR 120CrossRefGoogle Scholar.

⁴⁵ Swadling, W, ‘Case Comment: The Common Intention Constructive Trust in the House of Lords: An Opportunity Missed’ (2007) 123 LQR 511–17Google Scholar.

⁴⁶ Gardner (n 41) 422–44, 425; Etherton, T, ‘Constructive Trusts: A New Model for Equity and Unjust Enrichment’ (2008) 67 CLJ 265, 279CrossRefGoogle Scholar.

⁴⁷ Etherton, T, ‘Constructive Trust and Proprietary Estoppels: The Search for Clarity and Principle’ (2009) 73 Conveyancer 104–26Google Scholar.

⁴⁸ [2008] UKHL 55.

⁴⁹ Hopkins (n 43) 310, 336–7.

⁵⁰ This very interesting approach will not be discussed in detail in this article which focuses on the approaches applied by the courts in most cases.

⁵¹ McFarlane, B, The Structure of Property Law (Hart 2008) 767–81Google Scholar.

⁵² Harding, M, ‘Defending Stack v Dowden’ (2009) 73 Conveyancer 309, 321–2Google Scholar.

⁵³ Pawlowski, M, ‘Beneficial Entitlement: No Longer Doing Justice?’ (2007) 71 Conveyancer 354, 364Google Scholar.

⁵⁴ James v Thomas [2007] EWCA Civ 1212; Morris v Morris & Ors [2008] EWCA Civ 257; Fowler v Barron [2008] EWCA Civ 377.

⁵⁵ Bridge, S, ‘Case Comment: Jones v Kernott: Fairness in the Shared Home: The Forbidden Territory or the Promised Land’ (2010) 74 Conveyancer 324, 329Google Scholar; Piska, N, ‘Ambulatory Trusts and the Family Home: Jones v Kernot’ (2010) 24 TLI 87Google Scholar.

⁵⁶ Gardner, S and Davidson, KM, ‘The Future of Stack v Dowden’ 127 LQR (2011) 13, 14Google Scholar.

⁵⁷ ibid 13, 17–19.

⁵⁸ [2011] UKSC 53.

⁵⁹ With a possible exception of cohabitants who are also business partner Jones v Kernott [2011] UKSC 53 [31].

⁶⁰ Briggs, A, ‘Co-Ownership and an Equitable Non Sequitur’ (2012) 128 LQR 183–4Google Scholar criticized the usage of the term ‘joint tenants in equity’ at 43.

⁶¹ Jones v Kernott [2011]UKSC 53 at [25].

⁶² ibid [31].

⁶³ ibid [14] referring to Stack v Dowden [2007] UKHL 17 at [62].

⁶⁴ ibid [65–6].

⁶⁵ ibid at [65] Lord Kerr stressed the importance to keep imputing and inferring apart conceptually, at [75, 77]; at [78] per Lord Wilson.

⁶⁶ Gardner, S and Davidson, KM, ‘The Supreme Court on Family Homes’ (2012) 128 LQR 178, 180–1Google Scholar.

⁶⁷ Jones v Kernott [2011]UKSC 53 at 34 per Lady Hale, and Lord Walker.

⁶⁸ ibid [31, 47].

⁶⁹ [1991] 1 AC 107.

⁷⁰ Gardner and Davidson (n 56) 13, 15.

⁷¹ Jones v Kernott [2011] UKSC 53 at [16].

⁷² ibid [16, 17, 52].

⁷³ Oxley v Hiscock [2004] 3 All ER 703.

⁷⁴ Gardner and Davidson (n 66) 178; see already Roche, J, ‘Kernott, Stack, and Oxley Made Simple: A Practitioner's View’ (2011) 75 Conveyancer 123Google Scholar.

⁷⁵ Mee, J, ‘Case Comment – Jones v Kernott: inferring and imputing in Essex’ (2012) 76 Conveyancer 167, 178–80Google Scholar.

⁷⁶ J Mee ibid 180; see also critically George, R, ‘Case Comment – Cohabitant's Property Rights: When Is Fair Fair?’ (2012) 71 CLJ 39–42CrossRefGoogle Scholar.

⁷⁷ See also Pawlowski, M, ‘Case Comment – Imputed Intention and Joint Ownership: A Return to Common Sense: Jones v Kernott’ (2012) 76 Conveyancer 149–58Google Scholar; Yip, M, ‘The Rules Applying to Unmarried Cohabitants’ Family Home: Jones v Kernott’ (2012) 76 Conveyancer 159, 165–7Google Scholar.

⁷⁸ Murdoch v Murdoch [1975] 1 SCR 423, 438.

⁷⁹ Rathwell v Rathwell [1978] 2 SCR 436, 452, 474; see also Abella J in Quebec (Attorney General) v A 2013 SCC 5 at [310–11]

⁸⁰ See Kerr v Baranow 2011 SCC 10 at [22].

⁸¹ [1980] 2 SCR 834.

⁸² Burrows, A, The Law of Restitution (3rd edn, OUP 2011) 86–95Google Scholar.

⁸³ [1980] 2 SCR 834.

⁸⁴ Dickson, J—as he then was—had used the phrase first in his minority opinion in Rathwell v Rathwell [1978] 2 SCR 436Google Scholar.

⁸⁵ See Smith, L, ‘The Mystery of ‘Juristic Reason’ (2000) Supr Court L Rev (2d) 12, 211–44Google Scholar; Smith, L, ‘Demystifying Juristic Reasons’ (2007) 45 Canadian Business Law Journal 281–304Google Scholar; McInnes, M ‘The Test of Unjust Enrichment in Canada’ (2007) 123 LQR 34, 37Google Scholar; Hunt, CDL, ‘Unjust Enrichment Understood as Absence of Basis: A Critical Evaluation with Lessons from Canada’ (2009) Oxford University Comparative Law ForumGoogle Scholar <http://ouclf.iuscomp.org/articles/hunt.shtml> accessed 14 February 2013, part III.

⁸⁶ [1993] 1 SCR 980, 989–95.

⁸⁷ ibid 980, 989.

⁸⁸ [2004] 1 SCR, 629 SCC.

⁸⁹ Hunt (n 85).

⁹⁰ [2009] SCC 15.

⁹¹ [1980] QB 677.

⁹² Kerr v Baranow 2011 SCC 10 at [36–8].

⁹³ ibid [39].

⁹⁴ ibid [40–5].

⁹⁵ ibid [15–29].

⁹⁶ ibid [47–53, 55–7]; McInnes, M, ‘Cohabitation, Trusts and Unjust Enrichment in the Supreme Court of Canada’ (2011) 127 LQR 339, 341–2Google Scholar.

⁹⁷ Kerr v Baranow 2011 SCC 10 at [140, 155–60].

⁹⁸ ibid [87–100].

⁹⁹ ibid [84].

¹⁰⁰ Lower, M, ‘Case Comment – The Constructive Trust: From Common Intention to Relationship? Kerr v Baranow’ (2011) 75 Conveyancer 515, 520–1Google Scholar.

¹⁰¹ McInnes (n 96) 339, 342.

¹⁰² Comparative work on the trust has always had a great fascination for German lawyers Kötz, H, Trust und Treuhand (Vandenhoeck and Ruprecht 1963)Google Scholar; Zweigert and Kötz (n 19) 188–9; the German law of the Treuhandverhältnis has often been the subject of comparative research as well Beyerle, F, Die Treuhand im Grundriss des deutschen Privatrechts (Böhlaus 1932)Google Scholar; Siebert, W, Das rechtsgeschäftliche Treuhandverhältnis (Elwert 1933)Google Scholar; Coing, H, Die Treuhand kraft privaten Rechtsgeschäfts (CH Beck 1973)Google Scholar; Blaurock, U, Unterbeteiligung und Treuhand an Gesellschaftsanteilen (Nomos 1981)Google Scholar; Westebbe, A, Die Stiftungstreuhand (Nomos 1993)Google Scholar; Bachner, M, Der Constructive Trust (Dissertation Eigendruck 1995)Google Scholar; Grundmann, S, Der Treuhandvertrag (CH Beck 1997)Google Scholar; Bitter, G, Rechtsträgerschaft für fremde Rechnung (Mohr Siebeck 2006)Google Scholar; Löhnig, M, Treuhand (Mohr Siebeck 2006)Google Scholar; Becker, R, Die fiducie von Québec und der trust (Mohr Siebeck 2007)Google Scholar.

¹⁰³ OLG Köln, Neue Juristische Wochenschrift RR 1996, 1411; Wellenhofer, M, ‘Nach § 1302’ in Münchener Kommentar Bürgerliches Gesetzbuch, Familienrecht I (5th edn, CH Beck 2010)Google Scholar para 28.

¹⁰⁴ Ulmer, P, ‘§ 705’ in Münchener Kommentar Bürgerliches Gesetzbuch (5th edn, CH Beck 2009)Google Scholar paras 275–83.

¹⁰⁵ Section 1(1) Partnership Act 1890. Business relationships between spouses or family members have proved difficult for the courts Taylor v Mazorriaga [1999] EWCA Civ 1393; Ravindran v Rasanagayam [2001] EWCA Civ 365.

¹⁰⁶ BGHZ 8, 249.

¹⁰⁷ Ulmer (n 104) paras 275–88.

¹⁰⁸ BGH (1960) Neue Juristische Wochenschrift 58; 104; BGHZ 31, 197, 200–201; 84, 361, 367; BGH (1989) Zeitschrift für das gesamte Familienrecht 147, 148; BGH (1999) Neue Juristische Wochenschrift 2962; BGH (2006) Neue Juristische Wochenschrift 126.

¹⁰⁹ BGH (1965) Wertpapiermitteilungen 793.

¹¹⁰ Eves v Eves [1975] 1 WLR 1338.

¹¹¹ BGH (1996) Neue Juristische Wochenschrift RR 1473, confirmed in BGH (1997) Neue Juristische Wochenschrift 3371; BGH (2005) Neue Juristische Wochenschrift RR 1089, 1091.

¹¹² B Dauner-Lieb (n 14) 361–6; Bruch, A, ‘Zuwendungen unter Ehegatten: ein Überblick über Abgrenzungsfragen und Gestaltungsmöglichkeiten’ (2008) Mitteilungen der Bayrischen Notarkammer 173–82Google Scholar: Grziwotz, H, ‘Die zweite Spur: ein (neuer) Weg zur Gerechtigkeit zwischen Ehegatten’ (2000) Deutsche Notar-Zeitschrift 486–98Google Scholar; Haußleiter, M, ‘Zum Ausgleichsanspruch bei einer Ehegatteninnengesellschaft neben einem Anspruch auf Zugewinnausgleich’ (2006) Neue Juristische Wochenschrift 2741–73Google Scholar; Haas, U, ‘Ehegatteninnengesellschaft und familienrechtlicher Vertrag sui generis?’ (2002) Zeitschrift für das gesamte Familienrecht 205–11Google Scholar; Herr, T, Kritik der konkludenten Eheinnengesellschaft (Deutscher Anwaltverlag 2008)Google Scholar; Kogel, W, ‘Zugewinn oder Ehegatteninnengesellschaft? Eine Gratwanderung in der Vermögensauseinandersetzung’ (2006) Zeitschrift für das gesamte Familienrecht 1799–1805Google Scholar.

¹¹³ BGHZ 165, 1, 10.

¹¹⁴ ibid.

¹¹⁵ BGHZ 177, 193, 201, confirmed in BGH (2011) Neue Juristische Wochenschrift, 2880, 2881.

¹¹⁶ In a 2010 decision concerning donations of parents in law, the Bundesgerichtshof has applied section 313 BGB to the law of gifts BGHZ 184, 190. Whether the law of gifts will take on a new importance for transfers between spouses remains to be seen, critical Braeuer, M, ‘Zuwendungen innerhalb der Familie und gesetzlicher Zugewinnausgleich’ (2011) Familie Partnerschaft Recht, 75, 77–8Google Scholar; Herr, T, ‘Die neue Schwiegerelternrechtsprechung des BGH: mehr Dogmatik im Nebengüterrecht?’ (2010) Familienrechtsberater 308–12Google Scholar cautiously positive Kogel, W, ‘Rechtsprechungsänderung zu den schwiegerelterlichen Zuwendungen – der vorprogrammierte Gau im Zugewinnausgleich’ (2010) Familienrechtsberater 309–14Google Scholar; Schmitz, B, ‘Anmerkung’ (2010) Neue Juristische Wochenschrift 2207–8Google Scholar; Langenfeld, G, ‘Anmerkung’ (2010) Zeitschrift für Erbrecht und Vermögensnachfolge 376–7Google Scholar.

¹¹⁷ BGH (2003) Zeitschrift für das gesamte Familienrecht, 230; Wever, R, Vermögensauseinandersetzung der Ehegatten außerhalb des Güterrechts (5th edn, Gieseking 2009)Google Scholar n. 417.

¹¹⁸ Sandweg, HE, ‘Ehebedingte Zuwendungen und ihre Drittwirkung’ (1989) Neue Juristische Wochenschrift 1965–74Google Scholar.

¹¹⁹ Section 313(1) reads: ‘If circumstances upon which a contract was based have materially changed after conclusion of the contract and if the parties would not have concluded the contract or would have done so upon different terms if they had foreseen that change, adaptation of the contract may be claimed in so far as, having regard to all the circumstances of the specific case, in particular the contractual or statutory allocation of risk, it cannot be reasonably be expected that a party should continue to be bound by the contract in its unaltered form.’ Translation by Dannemann (n 134) 301–2. For a historic perspective see Mayer-Pritzl, R, ‘§§ 313–314 Störung der Geschäftsgrundlage’ in Historisch Kritischer Kommentar zum BGB Vol II (2), §§ 305–432 (Mohr Siebeck 2007)Google Scholar paras 305–432.

¹²⁰ With references to the case law Roth, GH ‘§ 242’ in Münchener Kommentar Bürgerliches Gesetzbuch (5th edn, CH Beck 2007)Google Scholar paras 57–70.

¹²¹ BGH (1997) Zeitschrift für das gesamte Familienrecht 933, 934; BGH Zeitschrift für das gesamte Familienrecht (1990) 600, 601; BGHZ 84, 361, 365; BGH Deutsche Notar-Zeitschrift (1992) 439, 440.

¹²² Lieb, M, Die Ehegattenmitarbeit (Mohr Siebeck 1970) 130Google Scholar.

¹²³ BGH (1982) Neue Juristische Wochenschrift 2236.

¹²⁴ BGHZ 77, 55, 58 confirmed by BGH (1992) Neue Juristische Wochenschrift 906, 907.

¹²⁵ Schulz, Critical W, ‘Vermögensauseinandersetzung der nichtehelichen Lebensgemeinschaft’ (2007) Zeitschrift für das gesamte Familienrecht 593–7Google Scholar, 595–7.

¹²⁶ BGHZ 177, 193.

¹²⁷ The decision frequently refers to the case law on married couples living in a regime of separation of property BGHZ 177, 193, 208–12.

¹²⁸ BGHZ 177, 193, 208–10; critical Gernhuber, J, ‘Die Mitarbeit der Ehegatten im Zeichen der Gleichberechtigung’ (1958) Zeitschrift für das gesamte Familienrecht 243, 246Google Scholar; Lieb, M, ‘§ 812’ Münchener Kommentar Bürgerliches Gesetzbuch (CH Beck 2004)Google Scholar paras 217–18.

¹²⁹ BGHZ 177, 193, 208.

¹³⁰ ibid, 193, 209.

¹³¹ BGH (2010) Neue Juristische Wochenschrift 868.

¹³² BGH (2011) Neue Juristische Wochenschrift 2880, 2882.

¹³³ Grziwotz, H, ‘Von der faktischen Lebensgemeinschaft zur Zusammenlebensgemeinschaft’ (2010) Familie Partnerschaft Recht 369–71Google Scholar; Grziwotz, H, ‘Anmerkung zum Urteil des BGH vom 9.7.2008’ (2008) Zeitschrift für das gesamte Familienrecht 1829–30Google Scholar; N Dethloff (n 6) 140–5; Löhnig, M, ‘Anmerkung zum Urteil des BGH vom 9.7.2008’ (2009) in Deutsche Notar-Zeitschrift 59, 62Google Scholar. An unmarried parent who cannot work because taking care of a child can ask for maintenance, however, until the child turns three; section 1615l BGB.

¹³⁴ Section 812(1) reads: ‘A person who obtains something by performance by another person [1st alternative] or in another way [2nd alternative] at the expense of this person without legal ground is bound to give it up to him [1st sentence]. The same obligation exists if the legal ground later lapses [1st alternative] or if the result does not occur which the performance had been aimed at to produce according to the content of the legal transaction [2nd alternative, 2nd sentence, condictio ob rem].’ Translation by Dannemann, G, The German Law of Unjustified Enrichment and Restitution (OUP 2009)CrossRefGoogle Scholar 308 (indication for alternative, sentence and condictio ob rem added). BGHZ 177, 193, 206–7; BGH Zeitschrift für das gesamte Familienrecht (2009) 849, 850–1; Lieb (n 128) para 119, fn. 51. Unjust enrichment will be discussed in detail below.

¹³⁵ RGZ 111, 151; Krebs, T, Restitution at the Crossroads: A Comparative Study (Routledge Cavendish 2000) 76–9Google Scholar; Dannemann, G, ‘Unjust Enrichment as Absence of Basis: Can English Law Cope?’ in Mapping the Law (OUP 2006) 363–77CrossRefGoogle Scholar.

¹³⁶ G Dannemann (n 134) 45–9.

¹³⁷ See on the debate on the application of the condictio ob rem Dannemann ibid, 45–9.

¹³⁸ At least, a statement of Viscount Simon LC in Fibrosa Spolka Akejna v Fairbairn Lawson Combe Barbour Ltd [1943] AC 32, 48 can be interpreted this way. See also Roxborough v Rothmans of Pall Mall Ltd (2001) 208 CLR 516; Burrows (n 82) 320–1, 398–9.

¹³⁹ Gernhuber, J and Coester-Waltjen, D, Familienrecht (6th edn, CH Beck 2010)Google Scholar section 20, para 27; Lieb (n 122) 40–9; Ulmer, P, ‘Vor § 705’ in Münchener Kommentar Bürgerliches Gesetzbuch (5th edn, CH Beck 2009)Google Scholar para 76.

¹⁴⁰ Gernhuber and Coester-Waltjen (n 139) section 19, Rn 89.

¹⁴¹ Lieb (n 122) 52.

¹⁴² Gernhuber, J ‘Die Mitarbeit der Ehegatten im Zeichen der Gleichberechtigung’ (1958) Zeitschrift für das gesamte Familienrecht 243, 245Google Scholar; see also Dauner-Lieb (n 14) 361, 362; Gernhuber and Coester-Waltjen (n 139) section 20, para 27; Wever (n 117) 628, 643.

¹⁴³ Leitmeier, L, ‘Die Zweckkondiktion – eigentlich Treu und Glauben?’ (2010) Neue Juristische Wochenschrift 2006Google Scholar.

¹⁴⁴ Schmidt, K, Gesellschaftsrecht (4th edn, Heymanns 2002)Google Scholar 1731, fn 20.

¹⁴⁵ Lower (n 100) 515, 520–1.

¹⁴⁶ Mee (n 75) 167, 178–80.

¹⁴⁷ Jones v Kernott [2011] UKSC 53 at [35, 57]; see also Gow v Grant [2012] UKSC 29 at [44–56].

¹⁴⁸ Midland Bank v Cooke [1995] 2 All ER 562.

¹⁴⁹ On ‘family law exceptionalism’ see the special issue of the (2010) 58 American Journal of Comparative Law 753 edited by J Halley and K Rittich.

¹⁵⁰ For English law see Etherton (n 47) 104–26.

¹⁵¹ Harding (n 52) 309, 314.

¹⁵² Hopkins (n 43) 310, 316–18.

¹⁵³ Peter v Beblow [1993] 1 SCR 980, 997.

¹⁵⁴ Kerr v Baranow 2011 SCC 10 at [34, 35].

¹⁵⁵ BGH (1999) Zeitschrift für das gesamte Familienrecht 1580; BGH (1997) Zeitschrift für das gesamte Familienrecht 933; BGHZ 127, 50,52; BGHZ 84, 361, 365, 368–369; BGH Zeitschrift für das gesamte Familienrecht (1988) 481; BGH (1990) Zeitschrift für das gesamte Familienrecht 855, 856; BGH (1972) Neue Juristische Wochenschrift 1972, 580; BGH Neue Juristische Wochenschrift (1974) 1554; the literature produced by both academics and practitioners is massive in this area. See only Wever (n 117); Schwab, D and Hahne, M, Familienrecht im Brennpunkt (Gieseking 2004)Google Scholar; Kogel, W, ‘§ 19’ Münchener Anwaltshandbuch Familienrecht (CH Beck 2002)Google Scholar; Dauner-Lieb (n 14) 361–6.

¹⁵⁶ Kerr v Baranow 2011 SCC 10 at [84].

¹⁵⁷ R Leckey (n 6) 48–72.

¹⁵⁸ Sanders, A, ‘Private Autonomy and Marital Property Agreements’ (2010) 59 ICLQ 571–92CrossRefGoogle Scholar.

¹⁵⁹ For an English introduction to the German constitutional law of marriage see Sanders, A, ‘Marriage, Same-Sex Partnership, and the German Constitution’ 13 German Law Journal (2012) 911, 915–23CrossRefGoogle Scholar; <http://www.germanlawjournal.com/index.php?pageID=11&artID=1448> accessed 10 December 2012.

¹⁶⁰ BVerfGE 105, 313, 348–50; for an English translation of the decision that accepted the civil partnership for homosexual couples as constitutional see <http://www.bundesverfassungsgericht.de/entscheidungen/fs20020717_1bvf000101en.html> accessed 7 December 2012.

¹⁶¹ BVerfGE 9, 20; BVerfGE 29, 166, 176; BVerfGE 105, 313, 350; <http://www.bundesverfassungsgericht.de/entscheidungen/fs20020717_1bvf000101en.html> accessed 7 December 2012 at [103]: ‘The duty of the state to promote marriage must orient itself towards the protective purpose of art 6.1 of the Basic Law. If the legislature itself, in creating norms, contributed to marriage losing its function, it would violate the requirement of promotion under art 6.1 of the Basic Law. Such a danger might exist if the legislature created another institution in competition with marriage, with the same function, and, for example, gave it the same rights and lesser duties, so that the two institutions were interchangeable.’ M Badura, ‘Art. 6 Abs. 1’ in T Maunz and G Dürig (eds), Grundgesetzkommentar Art. 6 Abs. 1 para 55 (CH Beck 2012).

¹⁶² BVerfGE 6, 15.

¹⁶³ For a critical evaluation see Manfredi, C, Judicial Power and the Charter: Canada and the Paradox of Liberal Constitutionalism (2nd edn, OUP 2001)Google Scholar chaps 3–5; For the influence of constitutional law in Germany see Kommers, D and Miller, R, The Constitutional Jurisprudence of the Federal Republic of Germany (3rd edn, Duke University Press 2012)Google Scholar.

¹⁶⁴ Miron v Trudel [1995] 2 SCR 418; Nova Scotia (Attorney General) v Walsh [2002] 4 SCR 325.

¹⁶⁵ 2013 SCC 5.

¹⁶⁶ Jones v Kernott [2011] UKSC 53 at [31].

¹⁶⁷ Gardner and Davidson (n 56) 13, 15.

¹⁶⁸ Lewis, J, Tennant, R and Taylor, J ‘Financial Arrangements on the Breakdown of Cohabitation’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009) 161, 165Google Scholar.

¹⁶⁹ Douglas, Pearce and Woodward (n 13) 139, 142–7.

¹⁷⁰ Kerr v Baranow 2011 SCC 10 at 26, referring to Dickson J in Pettkus v Becker [1980] 2 SCR 834, 834–844.

¹⁷¹ Gardner (n 41) 422–40; see also Abella J in Quebec (Attorney General) v A 2013 SCC 5 at [310–311].

¹⁷² Gardner and Davidson (n 66) 178–82; for a comparative view see Scherpe, JM (ed), Marital Agreements and Private Autonomy in Comparative Perspective (Hart 2012)Google Scholar.

¹⁷³ Harding (n 52) 309, 321–2; see also Mee (n 75) 167, 179.

¹⁷⁴ Satchwell v McIntosh 2006 SLT (Sh Ct) 117.

¹⁷⁵ Baumgartner v Baumgartner (1987) 164 CLR 137; Muschinski v Dodds (1985) 160 CLR 583.

¹⁷⁶ Gardner (n 41) 421, 437; Etherton (n 46) 265–87.

¹⁷⁷ Even if a right under a trust is not described as a property right—a right against a thing—but as a right against a right; McFarlane (n 51) 23–32.

¹⁷⁸ Case law and academic writing about this question is too extensive to give full credit to the discussion. See only Burrows (n 82) 168–98; Swadling (n 26) 72–102; Birks, P, Unjust Enrichment (2nd edn, OUP 2005) 180–204CrossRefGoogle Scholar; Millett, P, ‘Jones v Jones: Property or Unjust Enrichment’ in Burrows, A and Lord Roger of Earlsferry (eds), Mapping the Law (OUP 2006) 265–75CrossRefGoogle Scholar; Virgo, G, The Principles of the Law of Restitution (2nd edn, OUP 2006) 11–18CrossRefGoogle Scholar, 105–6, 569–76; Häcker, B, ‘Proprietary Restitution after Impaired Consent Transfers: A Generalised Power Model’ 68 CLJ (2009) 324–69CrossRefGoogle Scholar; Jaffey, P, The Nature and Scope of Restitution (Hart 2000)Google Scholar; Webb, C, ‘What is Unjust Enrichment?’ 29 OJLS 215–43CrossRefGoogle Scholar. A proprietary response to failure of consideration, however, is not considered appropriate even by most commentators who embrace proprietary responses to unjust enrichment. This point will be discussed below.

¹⁷⁹ Birks (n 178) 129–160; Meier, S, Irrtum und Zweckverfehlung (Mohr Siebeck 1999)Google Scholar; Meier, S. (2006) ‘No Basis: A Comparative View’ in Burrows, A and Lord Roger of Earlsferry (eds), Mapping the Law (OUP 2006) 343–61CrossRefGoogle Scholar; Baloch, TA, ‘The Unjust Enrichment Pyramid’ (2007) 123 LQR 636–53Google Scholar, cautious Häcker, B, ‘Still at the Crossroads’ (2007) 123 LQR 177, 182Google Scholar; critical Krebs, T, ‘In Defence of Unjust Factors’ in Johnston, D and Zimmermann, R (eds), Unjustified Enrichment: Key Issues in Comparative Perspective (CUP 2002) 76–100CrossRefGoogle Scholar; Burrows (n 82) 86–116; Sanders, A, ‘Absence of Basis: A German Perspective’ in Elliott, S, Häcker, B and Mitchell, C (eds), Restitution of Overpaid Tax (Hart 2013) 213Google Scholar; see for a Canadian perspective McInnes (n 85) 34–61, 37; Smith (n 85) 12, 211–44 the courts have left the question open; see Lord Walker of Gestingthorpe in Deutsche Morgan Grenfell Group PLC v IRC [2006] UKHL 19 [150]; less favourable: FII v CIR [2012] UKSC 19 at [162] per Lord Sumption.

¹⁸⁰ [1993] 1 SCR 980, 989.

¹⁸¹ Dannemann (n 135) 363–77.

¹⁸² Balfour v Balfour 2 KB [1919] 571; Ibbetson, D, A Historical Introduction to the Law of Obligations (OUP 1999) 232–3Google Scholar; Atiyah, PS, An Introduction to the Law of Contract (5th edn, OUP 1995) 156Google Scholar; McKendrick, E, Contract Law (5th edn, OUP 2012) 269–82Google Scholar.

¹⁸³ Burrows (n 82) 214–217; Krebs (n 135) 76; Tang, Hang Wu, ‘Restitution for Mistaken Gifts’ (2004) 20 JCL 1–28Google Scholar.

¹⁸⁴ See Haas, U and Holla, M, ‘Die enttäuschte Erberwartung’ (2002) Zeitschrift für Erbrecht und Vermögensnachfolge 169–70Google Scholar; it is not clear if the condictio ob rem can be applied at all if there is a contractual agreement between the parties. See with references to other literature and caselaw Schwab, M, ‘§ 812’ Münchener Kommentar Bürgerliches Gesetzbuch (5th edn, CH Beck 2009)Google Scholar para 377.

¹⁸⁵ Birks (n 178) 181–2; see also Chambers, R, Resulting Trusts (OUP 1997) 110, 155–70CrossRefGoogle Scholar.

¹⁸⁶ Chambers (n 185) 162; see for a summary of this position Burrows (n 82) 174–5.

¹⁸⁷ Burrows (n 82) 176–9; Edelman, J and Bant, E, Unjust Enrichment in Australia (OUP 2006) 70–72, 399–402Google Scholar.

¹⁸⁸ Burrows (n 82) 398.

¹⁸⁹ BGHZ 115, 261, 263–4; Welker, G, Bereicherungsausgleich wegen Zweckverfehlung (CH Beck 1974) 110–11CrossRefGoogle Scholar; Lieb (n 128) paras 217–18.

¹⁹⁰ BGH Zeitschrift für das gesamte Familienrecht (2009) 849, 850.

¹⁹¹ Lieb (n 122) 116–17; cautious Dethloff, N, ‘Anmerkung’ (2009) Juristenzeitung, 418, 419CrossRefGoogle Scholar; more optimistic Sorge, C, ‘Condictio ob rem und Rückabwicklung gemeinschaftsbezogener Zuwendungen in nichtehelichen Lebensgemeinschaften’ (2011) Juristenzeitung 660–8CrossRefGoogle Scholar.

¹⁹² Burns v Burns [1984] 2 WLR 582.

¹⁹³ BGHZ 177, 193, 202, 204; critical Grziwotz, H, ‘Anmerkung zum Urteil des BGH vom 9.7.2008’ (2008) Zeitschrift für das gesamte Familienrecht 1829–31. 1830)Google Scholar; Dethloff (n 6) 140–5.

¹⁹⁴ Peter v Beblow [1993] 1 SCR 980, 989–995.

¹⁹⁵ Kerr v Baranow 2011 SCC 10 at [59–69].

¹⁹⁶ ibid [69].

¹⁹⁷ McInnes (n 96) 339, 342.

¹⁹⁸ Harding would describe it as ‘communitarian’ Harding (n 52) 309, 321–2.

¹⁹⁹ The UK Supreme Court also demands legislative action Gow v Grant [2012] UKSC 29 at [44–56].

²⁰⁰ See, for example, Lord Browne Wilkinson in Kleinwort Benson LTD. v Lincoln City Council [1998] 4 All ER 513 per Lord Browne-Wilkinson: ‘The theoretical position has been that judges do not make or change law: they discover and declare the law which is throughout the same. According to this theory, when an earlier decision is overruled the law is not changed: its true nature is disclosed, having existed in that form all along. This theoretical position is, as Lord Reid said, a fairy tale in which no-one any longer believes. In truth, judges make and change the law. The whole of the common law is judge-made and only by judicial change in the law is the common law kept relevant in a changing world.’ See also US Supreme Court Justice Storey in Swift v Tyson 41. U.S. (16 Pet.) 1, 18 (1834) critical Justice Holmes Erie RR v Tompkins 304 U.S. 64, 78 (1938).

²⁰¹ Eisenberg, MA, The Nature of the Common Law (Harvard University Press 1988) 4Google Scholar; Barak, A, The Judge in a Democracy (Princeton University Press 2008) 155–8Google Scholar; Alexander, L and Sherwin, E, ‘Judges as Rule Makers’ in Edlin, D (ed), Common Law Theory (CUP 2007) 27CrossRefGoogle Scholar; Gardner, J, ‘Some Types of Law’ in Edlin, D (ed), Common Law Theory (CUP 2007) 51, 72–5Google Scholar.

²⁰² See for the differences and similarities of legal interpretation in Germany and England Vogenauer, S, Die Auslegung von Gesetzen in England und auf dem Kontinent I/II (Mohr Siebeck 2001)Google Scholar.

²⁰³ BVerfG (2012) Juristenzeitung 1065, 1068–70—Delisting decision. See also BVerfGE 34, 269 (1973); BVerfGE 82, 6, 11–14 (1990); BVerfGE 128, 193, 210 (2011).

²⁰⁴ Sauveplanne, JG, ‘Codified and Judgemade Law’ in van Wetenschappen, Koninklijke Nederlandse Akademie (ed) Mededelingen (B V Noord-Hollandsche Uotgevers Maatschappij 1982) 93, 111–20, 127Google Scholar.

²⁰⁵ Goetz, A, ‘Das Delisting-Urteil des BVerfG-freie Bahn für Erleichterungen des Börsenrückzugs?’ (2012) BB, 2767, 2768Google Scholar; Jachmann, M, ‘Art. 95 GG’ in Maunz, T and Dürig, G (eds), Grundgesetz Kommentar (66th edn, CH Beck, 2012)Google Scholarn. 15.

²⁰⁶ Brocker, L ‘Rechtsprechungsänderung und Vertrauensschutz’ (2012) Neue Juristische Wochenschrift 2996Google Scholar.

²⁰⁷ The Federal Constitutional Court has stressed that the doctrinal quality of case law is not a question of constitutional law; BVerfG (2012) Juristenzeitung 1065, 1069.

²⁰⁸ Alexander and Sherwin (n 201) 27, 33.

²⁰⁹ Harding (n 52) 309, 317–18 referring to Dworkin's distinction between policy and principle; Dworkin, R, Taking Rights Seriously (Duckworth 1977)Google Scholar Chap 4.

²¹⁰ Pleck (n 2) 229–230; Burgoyne and Sonnenberg (n 12) 89, 93–94, 105; Douglas, Pearce and Woodward (n 13) 139, 149–51.

²¹¹ Within the European Union though, there can be a duty to transpose a directive into national law.

²¹² Harding (n 52) 309, 321–2.

²¹³ 2013 SCC 5.

²¹⁴ 2013 SCC 5 at [248–61, 271–73, 413, 422, 435].

²¹⁵ Quebec (Attorney General) v A 2013 SCC 5 at [283–381] per Abella J.

²¹⁶ ibid [291–311] per Abella J.

²¹⁷ ibid [278] per LeBel J and at [449] per McLachlin CJ.

²¹⁸ See only Law Commission (n 10); Schwenzer, I and Dimsey, M, Model Family Code from a Global Perspective (Intersentia 2006)Google Scholar; Dethloff (n 6) 131.

²¹⁹ Property (Relationships) Act 1976, as of 2009 <http://www.legislation.govt.nz/act/public/1976/0166/latest/DLM440945.html> accessed 7 December 2012.

²²⁰ Property (Relationships) Act 1984, as of 2011 <http://www.austlii.edu.au/au/legis/nsw/consol_act/pa1984298/> accessed 7 December 2012.

²²¹ Family Law (Scotland) Act 2006 <http://www.legislation.govuk/asp/2006/2/pdfs/asp_20060002_en.pdf > accessed 7 December 2012.

²²² Part 15 Civil Partnership and Certain Rights and Obligations of Cohabitants Act 2010 <http://www.irishstatutebook.ie/2010/en/act/pub/0024/index.html> accessed 7 December 2012.

²²³ A registered civil partnership is available to same sex as well as mixed sex couples and provides certain rights, though not the same level of protection as marriage.

²²⁴ Law Commission (n 10).

²²⁵ Wasoff, F, Miles, J and Mordaunt, E, Legal Practitioners' Perspectives on the Cohabitation Provisions of the Family Law Scotland Act 2006 (CRFR 2011)Google Scholar 21, 51 <http://www.crfr.ac.uk/reports/Cohabitation%20final%20report.pdf> accessed 12 December 2012. See also Miles, J, ‘Cohabitation: Lessons for the South from North of the Border?’ (2012) 71 CLJ 492, 494CrossRefGoogle Scholar.

²²⁶ Miron v Trudel [1995] 2 SCR 418, 498.

²²⁷ 2013 SCC 4 at [334, 373–5].

²²⁸ Law Commission (n 10) 9.

²²⁹ See with further references Antokolskaia, M, ‘Economic Consequences of Informal Heterosexual Cohabitation from a Comparative Perspective: Respect Parties' Autonomy or Protection of the Weaker Party’ in Verbeke, A et al. (eds), Confronting the Frontiers of Family and Succession Law (Intersentia 2012) 41, 48–9Google Scholar.

²³⁰ Sanders (n 158) 571.

²³¹ 2013 SCC 5 [248–61, 271–3, 413, 422, 435]; see also Nova Scotia (Attorney General) v Walsh, 2002 SCC 83, [2002] 4 SCR 325 at [54, 57].

²³² Since a couple with a child forms a family, which is protected under art 6(1) of the German constitution like marriage, no constitutional problems should prevent German regulation in this context.

²³³ A problem the couple in Quebec (Attorney General) v A 2013 SCC 5 settled outside of court, at [6].

²³⁴ White v White [2001] 1 AC 596; Miller v Miller, McFarlane v McFarlane [2001] UKHL 24; Miles, J and Probert, R, ‘Sharing Lives, Dividing Assets’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009)Google Scholar 3, 7.

²³⁵ Barlow, A, ‘Legal Rationality and Family Property’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009) 303, 317–19Google Scholar.

²³⁶ Law Commission (n 10).

²³⁷ Family Law (Scotland) Act 2006 <http://www.legislation.govuk/asp/2006/2/pdfs/asp_20060002_en.pdf> accessed 7 December 2012. See for empirical reasearch on the legislation and its implications for reform in England and Wales Wasoff, Miles and Mordaunt (n 225). See also Gow v Grant [2012] UKSC 29, Miles, J ‘Cohabitation: Lessons for the South from North of the Border?’ 71 CLJ (2012) 492–5CrossRefGoogle Scholar.

²³⁸ Schwenzer and Dimsey (n 218).

²³⁹ On gender inequalities in relation to paid and unpaid work: Scott, J and Dex, S, ‘Paid and Unpaid Work’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009) 41–57Google Scholar.

²⁴⁰ Finney, A, ‘The Role of Personal Relationships in Borrowing, Saving and Over-indebtedness’ in Miles, J and Probert, R (eds), Sharing Lives, Dividing Assets (Hart 2009) 107, 125Google Scholar.

²⁴¹ Burgoyne and Sonnenberg (n 12) 89, 97.

²⁴² Property (Relationships) Act 1984, as of 2011 <http://www.austlii.edu.au/au/legis/nsw/consol_act/pa1984298/> accessed 7 December 2012.

²⁴³ Family Law (Scotland) Act 2006 <http://www.legislation.govuk/asp/2006/2/pdfs/asp_20060002_en.pdf > accessed 7 December 2012.

²⁴⁴ Part 15 Civil Partnership and Certain Rights and Obligations of Cohabitants Act 2010 <http://www.irishstatutebook.ie/2010/en/act/pub/0024/index.html> accessed 7 December 2012.

²⁴⁵ See Radmacher v Granatino [2010] UKSC 42.

²⁴⁶ See Hartshorne v Hartshorne [2004] 1 SCR 550, 2004 SCC 22.

²⁴⁷ For a comparative view of prenuptial agreements see Scherpe (n 172); Sanders (n 158) 571–603.