connivance

Definition from Nolo’s Plain-English Law Dictionary

1) Ignoring another person's wrongdoing, for example, by indirectly condoning an illegal act by another person. 2) In family law, a (somewhat archaic) defense that says that a person making claims against a spouse connived in the spouse's bad behavior. For example, a husband who invites his wife's lover along on vacation may have connived in her adultery, and if he tried to gain an advantage in the divorce as a result, she could assert his connivance as a defense.

Definition provided by Nolo’s Plain-English Law Dictionary.