exploit a loophole

Translations
воспользоваться лазейкой
He was able to exploit a loophole in the law to avoid paying taxes.
Он смог воспользоваться лазейкой в законе, чтобы избежать уплаты налогов.
Definitions
To take advantage of a gap, ambiguity, or oversight in a rule, law, or system in order to achieve a benefit or avoid a restriction, often in a way that is technically legal but considered unfair or unethical.
Words
exploit

verb
использовать
a

article or possessive pronoun
неопределённый артикль
loophole

noun
лазейка