vexatious litigation

English Thesaurus

1. litigation shown to have been instituted maliciously and without probable cause (noun.act)

hypernym	:	judicial proceeding, litigation,
definition	:	a legal proceeding in a court; a judicial contest to determine and enforce legal rights (noun.act)

domain category	:	jurisprudence, law,
definition	:	the collection of rules imposed by authority (noun.group)