O'Brien v MGN Ltd [2001] EWCA Civ 1279 is an English contract law case, concerning incorporation of terms through reasonable notice.

MGN pointed to "Rule 5", which said there would be a draw where more prizes were claimed than available.

She noted that Rule 5 was no great burden on the claimant, as in Interfoto, nor excluding liability for injury like Thornton, but simply deprived a windfall.[1]: Para.

21  She also noted that in the test for incorporation, the words "onerous or unusual" are not "terms of art".[1]: Para.

Sir Anthony Evans was doubtful that judge's reasons were right and thought the rule was onerous enough to require more notice, but he agreed, nevertheless, that the appeal should be dismissed.[1]: Para.