It is a part because you use contract law to determine the rights of the parties under a contract, and a license is a type of contract. A person who owns IP and licenses it to another does so through a contract. Thus, because detrimental reliance is part of contract law it is part of IP law as well.

An oral license is still a license. It's not an "at my own risk" where I am relying on a license and the stated policy of the IP holder; it's a matter of detrimental reliance. Paramount should not be able to profit off the grant of such licenses (through goodwill, free publicity for the Star Trek universe, etc.) and…