Australia’s Matt Jones, Phil Mickelson, Bryson DeChambeau and other LIV Golf players have filed an antitrust lawsuit against the PGA Tour. The Wall Street Journal was the first to report the matter.

The players are challenging their suspensions by the tour for defecting to the Saudi-backed circuit. Three of those in the lawsuit—Talor Gooch, Hudson Swafford and Jones—are attempting to receive a temporary restraining order that would allow them to play in next week’s FedEx Cup Playoffs. All three would have qualified for the tour’s postseason had they not been suspended.

One of the provisions in the PGA Tour Player Handbook and Tournament Regulations is that each PGA Tour member acknowledges the commissioner, the tour’s policy board and the appeals committee have the authority to permanently ban a member from playing in a tour co-sponsored, approved or coordinated tournaments if the member violates its regulations. The handbook also provides that a player ceases to be a member of the PGA Tour if, in the judgment of the policy board, the member commits a serious breach of the Tournament Regulations, the PGA Tour’s Code of Ethics, or otherwise conducts himself in a manner unbecoming of a professional golfer.

One such regulation generally prohibits tour players from playing in events when there is a PGA Tour-approved or sponsored event taking place at the same time. Per the handbook, players who reach the 15-event minimum (which members must meet as a condition of their membership voting rights) are eligible for three conflicting-event releases per season, which is why so many tour players were allowed to play in the Saudi Invitational earlier this year. However, the regulations also state such requests can be denied.

The PGA Tour announced it has suspended those who defected to LIV Golf following their participation in the inaugural LIV Golf event in London. “As you know, players listed below did not receive the necessary conflicting event and media rights releases—or did not apply for releases at all—and their participation in the Saudi Golf League/LIV Golf event is in violation of our Tournament regulations,” read a memo from PGA Tour commissioner Jay Monahan. “The same fate holds true for any other players who participate in future Saudi Golf League events in violation of our Regulations.”

The complaint and application for a temporary restraining order were filed in ​​the US District Court for the Northern District of California. Others named in the lawsuit include Ian Poulter, Abraham Ancer, Carlos Ortiz, Pat Perez, Jason Kokrak and Peter Uihlein. LIV Golf members like Dustin Johnson, Patrick Reed and Kevin Na were not named, as they have resigned their PGA Tour memberships.

The tour is adamant they have the legal authority to issue disciplinary measures, and LIV Golf CEO Greg Norman has openly expressed his desires for players to challenge that authority. Norman additionally telegraphed his litigation threats in an open letter to the tour.

Last month LIV Golf members won a temporary order to play in Scottish Genesis Open, an event co-sanctioned by the PGA Tour and DP World Tour.

The PGA Tour has not responded to a Golf Digest request for comment.