Short answers, pulled from the story.
The concept of numerus clausus traces back to Roman legal traditions where early jurists began distinguishing between property rights and personal claims. F. Parisi notes in a 2005 research paper that this distinction shaped how courts would later treat ownership versus contractual obligations.
English courts established that individuals could not freely create new categories of property rights without judicial recognition during Keppell v Bailey in 1834 and again in Hill v Tupper in 1863 as a matter of public policy. Lord Wilberforce offered a more open approach in National Provincial Bank Ltd v Ainsworth in 1965 yet maintained the core limitation.
Under current English law fourteen specific property rights exist within the numerus clausus framework including freehold ownership easements restrictive covenants leases mortgages rights under trusts licenses coupled with an interest profit a prendre rentcharges rights of entry estate contracts options pre-emption rights mere equities home rights. Freehold ownership remains the most fundamental form granting full control over land.
In German law the numerus clausus principle carries constitutional weight rather than relying solely on judicial precedent. A. Peukert's 2008 work highlights how this framework limits both the number and content of property rights through typological constraints known as Typenzwang and Typenfixierung.
France and Spain stand out as notable exceptions where the principle applies differently or less strictly compared to other European states. B. Akkermans documented these differences in a 2008 publication covering Antwerpen Oxford and Portland while Karel Eliáš discussed possession laws in NOZ during 2014 highlighting regional divergences.