You already know the answer: When they’re plaintiffs:

A Sparks pediatrician has sued an insurance provider, claiming it bilked thousands of northern Nevada doctors out of "tens of millions of dollars" by failing to pay claims and forcing them into "one-sided" contracts.

Dr. Kevin Windisch filed the class-action lawsuit in U.S. District Court in Reno against Hometown Health Plan and Renown Health.

. . . .

In addition to seeking compensatory and punitive damages, the suit asks the court for an injunction preventing the company from engaging in alleged improper practices affecting doctors.

Source: Sparks pediatrician sues insurance provider - Las Vegas Sun

I’m in no way criticizing the doctor for filing this lawsuit.  If the allegations are true, he should sue.  But the double-edged sword is that he should also be subject to being sued if he commits malpractice.