fall foul

Verb

fall foul (third-person singular simple present falls foul, present participle falling foul, simple past fell foul, past participle fallen foul)

1. (archaic, idiomatic) To collide; to conflict with; to attack (+ on, of, upon)
   • If they be any ways offended, […]they fall foul.1624, Democritus Junior [pseudonym; Robert Burton], The Anatomy of Melancholy: […], 2nd edition, Oxford, Oxfordshire: […] John Lichfield and James Short, for Henry Cripps, →OCLC
   • He was, literally speaking, drunk; which circumstance, together with his natural impetuosity, could produce no other effect than his running immediately up to his daughter, upon whom he fell foul with his tongue in the most inveterate manner [...]1749, Henry Fielding, The History of Tom Jones, a Foundling, volume (please specify |volume=I to VI), London: A[ndrew] Millar, […], →OCLC, book V
2. (idiomatic) To be defeated or thwarted (by); to suffer (+ of)
   • Sky News fell foul of its own woolly reporting on Tuesday, when it reported "human remains" had been found on Saddleworth Moor. Ever keen to spin a good yarn, they immediately linked the story to moors murderers Ian Brady and Myra Hindley - only for the police to emerge seven hours later and...2008, The Guardian, Media Monkey, 4 Aug 2008
   • If Chelsea were to fall foul of profit and sustainability, they would be expected to cite unforeseen circumstances, much as some clubs have claimed Covid writedowns: their books would have been sound but for the pandemic.March 11 2022, David Hytner, “Chelsea are in crisis but there is no will to leave club on their knees”, in The Guardian