Before no-fault grounds, marital fault was required for a divorce to be granted. Some couples may have wanted to divorce, but neither of them had committed any of the traditional faults: adultery, cruelty, desertion, imprisonment, etc. In order to obtain the divorce, they "colluded" or agreed to say that one of them had committed a fault that would give rise to divorce. Usually this was a claim of adultery by the husband. The couple essentially was trying to defraud the court. If before the divorce one spouse wanted to back out of the divorce, he or she could claim collusion and reveal the mutual agreement.