Numerus clausus (law)

The numerus clausus is a concept of property law which limits the number of types of right that the courts will acknowledge as having the character of "property". Several consequences follow from a right having the nature of property, as opposed to being a personal right, like a contract or obligation to pay compensation. Historically, the law has given privileged remedies to the holders of property rights over personal claims. These have included priority in payment from an insolvent debtor, a greater likelihood of being awarded specific performance, and security in remaining in possession of land or some other asset against termination of the right to possess. It holds especial importance in land law and corporate law.
History.
The numerus clausus principle has its roots in Roman law.
England & Wales.
In the United Kingdom, and particularly in the jurisprudence of the English courts, it is well established that individuals cannot freely create new categories of property right themselves: it has to be recognised by courts. This was held to be true in the 19th century in "Keppell v Bailey" and "Hill v Tupper" as a matter of public policy. In the 20th century, in "National Provincial Bank Ltd v Ainsworth" with a more open approach, Lord Wilberforce stated that
A widely held view is that a "numerus clausus", or a property right limit, serves to protect wealth in the scope where it already exists, and does not need extension. This tends to be contested on the basis acknowledgement of property rights simply masks a privilege for people who have enough bargaining power to exercise the freedom of contract for the various privileges that property rights confer, such as priority in insolvency, security of tenure, a right to trace or follow an asset, and a greater likelihood of specific performance as a remedy.
Under English law today, there are fourteen property rights in the "numerus clausus", as follows.
Before the Law of Property Act 1925, the life estate and the entail would have also counted as property rights, but they were abolished except as beneficial interests under a trust.
Germany.
In German law, the "numerus clausus" principle has a constitutional foundation and limits property rights in their number (Typenzwang) and content (Typenfixierung).
Europe.
Other European states show equal doctrines.
Theory.
There are competing views about the desirability of having a limited "numerus clausus" of property rights, as well as what counts as having a proprietary quality.