In United States copyright law, the principle of requiring originality for copyright protection was invoked in the 1991 ruling of the United States Supreme Court in "Feist Publications v. Rural Telephone Service". The court opinion stated that copyright protection could only be granted to "works of authorship" that possess "at least some minimal degree of creativity". As such, mere labor ("sweat of the brow") is not sufficient to establish a copyright claim. For example, the expression of some obvious methods of compilation and computation, such as the Yellow Pages or blank forms, cannot receive a copyright (demonstrated in "Morrissey v. Procter & Gamble"), but sufficiently original elements within the work itself can still be eligible for protection.