The Court’s right wing questioned OSHA’s authority to enforce President Joe Biden’s vaccine mandate Friday.

The U.S. Supreme Court is hearing arguments against President Joe Biden’s mandate that large companies in the U.S. require Covid-19 vaccines, and some of the court’s conservative members are questioning the legality of the order.

The court’s right-wing has questioned whether the Occupational Safety and Health Administration has the authority to require 80 million workers get shots or weekly tests.

The justices grilled the attorneys representing both sides during a special argument session Friday. 

The court has approved targeted vaccine mandates issued by state and local officials in recent hearings, rejecting religious objections multiple times in the process. 

But conservatives on the court are questioning whether OSHA should be overseeing Biden’s wide-ranging mandate. 

“[The pandemic] sounds like the sort of thing that states will be responding to or should be, and that Congress should be responding to or should be, rather than agency by agency the federal government and the executive branch acting alone,” Chief Justice John Roberts said, according to Bloomberg

The OSHA rule is set to go into effect Monday, but the agency has said it won’t issue citations to employers until Feb. 9, if they are trying in good faith to comply with the testing requirements.

The court’s ruling is not expected for a few days. 

Biden’s mandate is part of a plan to increase vaccination levels in a country that currently has a 62% full vaccination rate with only 35% receiving a booster, according to the Centers for Disease Control and Prevention. 

The court is also considering a separate mandate that would require shots for workers in nursing homes and other facilities that receive Medicare and Medicaid payments from the government.