To do that legally in the United States, for instance, you would need to..
- Overturn the Due Process Clause.
- Overturn the Equal Protection Clause.
- Overturn the "All persons born" clause...

...and probably a bunch of other crap. Internationally, you'd have to gut the ICCPR to get "different rules for different kinds." Most states, you'd have to gut their basic human and civil rights charters.

Why not just make it illegal for everybody? Why have a class that the important people can shit on and forget about?