Fee fights among plaintiffs attorneys in multidistrict litigation have forced more federal judges in recent cases to wade into the disputes — with practically no case law to guide them.

Within the last year, attorney fee fights in MDLs have erupted in personal injury and wrongful-death cases filed over Durom Cup hip implants, General Motors Co.’s ignition-switch defects and laparoscopic uterine surgical tools called power morcellators. There are few appellate decisions on the matter and, in at least two recent cases, the fights have ended with failed petitions before the U.S. Supreme Court.