A New Jersey judge has sanctioned two firms, Paul, Weiss, Rifkind, Wharton & Garrison and Lowenstein Sandler, for pursuing a “frivolous” and “ridiculous” legal claim on behalf of billionaire Ronald Perelman against his 85-year-old ex-father-in-law.

Perelman had alleged that Robert Cohen, the father of Perelman’s ex-wife, Claudia Cohen, who died in 2007, had promised Ms. Cohen that she would receive one half of Mr. Cohen’s estate.