From Longman Dictionary of Contemporary Englishfall foul of somebody/somethingfall foul of somebody/somethingANGRYILLEGALto do something which makes someone angry or which breaks a rule, with the result that you are punished He is worried that his teenage kids will fall foul of the law. → fall
Examples from the Corpus
fall foul of somebody/something• Edwards fell foul of the authorities and was ordered to leave the country. 