The analysis contained in this book has shown the impact of legal doctrine on legal development. English, German and Austrian law have historically developed in a path-dependent fashion. The path along which that development took place was shaped by legal doctrine: in all three jurisdictions, the legal environment that existed when securities were first issued determined their legal nature.

A distinction needs to be made between the factors that cause change to the law and the form in which the law absorbs the need for change. The need for reform is triggered by causes which also lie outside the law, and these causes are not analysed in this book. The book is rather based on the assumption that politics, economics, culture, social and commercial norms can bring about a need to change legal rules. Once a need for the law to accommodate change has emerged, however, the reform process has historically been shaped by legal doctrine. The legal systems analysed in this book did not construct new rules from scratch; rather, they modified the existing legal doctrine. Moreover, the lawyers charged with participating in reform by drafting the underlying legal rules favoured reform that required little modification of existing rules over reform that required significant change.

This pattern of change is inherent in the law. One reason explaining why lawyers prefer to modify existing rules rather than drafting new rules is that legal rules are necessarily incomplete: it is impossible to draft law that anticipates all the factual issues that will appear in the future.