Champerty

Definition from Nolo’s Plain-English Law Dictionary

An agreement between the party suing in a lawsuit (the plaintiff) and another person, who agrees to finance and carry the lawsuit in return for a percentage of the recovery. In some states, champerty is illegal. However, it is also the basis for the legal and commonly accepted practice of contingency fee arrangements with attorneys, who represent their clients and are paid from any award or settlement the plaintiff receives in the suit.

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