Karl,
They have all of the legal weight of a Jim Flem-o-gram. Then so does ARIN's and the IANA's ability to control and delegate addresses.
No. ARIN (et al) and the IANA have the ability to control/delegate addresses because by and large, the people who use the Internet, in particular, Internet service providers, mutually agree they have that ability. In other words, the registries are an (arguably) neutral forum which allow end users and service providers to agree who "owns" what address space instead of establishing who has the ability to use addresses in an n^2 multi-lateral fashion. As the Internet service provider community has found it easier to use the registries to impose certain policies/restrictions than to implement those restrictions themselves unilaterally, the registries have become the body that implements allocation policies. If you do not like these policies, your argument is with the Internet service provider community, which strangely enough, now is explicitly in a position to modify those policies. Regards, -drc