The Supreme Court will meet in a highly unusual session Friday to hear arguments on two Biden administration measures intended to help stop the spread of Covid in the nation’s workplaces.

The justices were not scheduled to return to the courtroom until Jan. 10, but they agreed late last month to take up emergency appeals involving the federal vaccination or testing requirements for large employers and the vaccination mandate for some health care workers.

In recent months, the court has declined to block vaccination mandates for students at Indiana University, teachers in New York, and health care workers in Maine, Massachusetts and New York. Those were rules imposed by states, which have broader authorities known as police powers to protect public health.

But in the last term, the court said federal law did not permit the Centers for Disease Control and Prevention to impose a nationwide ban on evictions. The cases to be heard Friday involve the specific authorities of two other federal agencies.

The court will consider whether the Occupational Safety and Health Administration has the legal power to require that businesses with 100 or more employees insure that those employees are vaccinated or that unvaccinated workers wear masks and show negative Covid test results at least once a week. Employees who work at home, alone or outdoors are exempt.