That case, Warner-Lambert Pharmaceutical v. John J. Reynolds, actually hinged on the fact that there was no patent license involved. Listerine's formula was a secret, and Jordan Lambert offered its creator royalties if he would share it with him. Later, the formula became widely known and Warner-Lambert wanted out of the deal since they were no longer getting any advantage from it. They sued to get out of their contract and recover past payments, citing patent cases as support for the idea that they should be set free of their obligations. The judge ruled that with patents, there is an understanding from the outset that they are paying for access to a time-limited monopoly, while the contract in this case was pretty clear about not having a termination date other than "whenever they stop making Listerine".

Source: http://law.justia.com/cases/federal/district-courts/FSupp/17...