Primates are regulated in a hierarchical fashion starting at the top with Federal regulations. Primates with federal or state permits must still meet local and city requirements.
None of these levels may be bypassed for those who breed or exhibit monkeys, but federal permits are not required for pets or privately kept colony monkeys.
All other regulations apply to everyone and monkey owners need to check with state fish and wildlife departments, county animal control agencies and town planning commissions for possible requirements or restrictions on primates.
Although the same federal laws apply to the entire country, each state has the autonomy to regulate separately from all others. Very few states are regulation free at the state level.
Each local county has this same autonomy, as does each town or city. Requirements at a local or city level range from none at all to a complex set of procedures involving yearly hearings with your immediate neighbors in order to renew your permit.
Often laws regarding the keeping of exotic animals are quietly passed behind the closed doors of legislature without our even knowing of it. By the time they are made public knowledge, it is usually more difficult to influence or reverse them.
Not all primate owners become "grandfathered" when laws change. This applies particularly at the local level.
Consequences for illegally kept monkeys vary from confiscation to very little consequence to monkey or owner.