term:

Champerty

champerty n

pl: -ties
[Anglo-French champartie bargaining for a share of disputed property, from champart share of crops paid as rent, share of property in dispute, from champ field + part portion]
: an unenforceable agreement by which a person with otherwise no interest in a lawsuit agrees to aid in or carry on its litigation in consideration of a share of the subject matter of the suit (as property or damages) compare maintenance