Demonstrators hold signs during a protest against Covid-19 mandates outside the General Motors (GM) Tech Center in Warren, Michigan, U.S., on Wednesday, Nov. 3, 2021.Mathew Hatcher | Bloomberg | Getty ImagesA federal appeals court has called President Joe Biden’s vaccine and testing requirements for private businesses “fatally flawed” and “staggeringly overbroad,” arguing that the requirements likely exceed the authority of the federal government and raise “serious constitutional concerns.”The U.S. Court of Appeals for the Fifth Circuit, in an opinion issued Friday evening, reaffirmed its decision to press pause on the implementation of the requirements, in another sign that they may not survive judicial scrutiny.The appellate court, considered one of the most conservative in the country, originally halted the requirements on Nov. 6 pending review, in response to challenges by the Republican attorneys general of Texas, Louisiana, Mississippi, South Carolina and Utah, as well as several private companies.While the court has not yet ruled on the constitutionality of the requirements, the three-judge panel made clear that the lawsuits seeking to overturn the mandates “are likely to succeed on the merits.” They criticized the requirements as “a one-size-fits-all sledgehammer that makes hardly any attempt to account for differences in workplaces (and workers).”The Occupational Safety and Health Administration, which polices workplace safety for the Labor Department, developed the requirements under emergency authority established by Congress. That authority allows the agency to shortcut the process to issue workplace safety and health standards, which normally years.OSHA can use its emergency authority if the Labor Secretary determines that a new safety or health standard is necessary to protect workers from a “grave danger” posed by a new hazard. The judges on Friday questioned whether Covid poses a grave danger to all the workers covered by the requirements, and argued that OSHA already has tools it can use short of a sweeping emergency safety standard.The Biden administration had asked the court on Monday to lift the pause, warning that delaying implementation “would likely cost dozens or even hundreds of lives per day” as the virus spreads. White House officials have repeatedly said that Covid clearly poses a grave danger to workers, pointing to the staggering death toll from the virus and the high levels of transmission in counties across the U.S.More than 750,000 people have died in the U.S. from the virus since the pandemic began and more than 46 million have been infected, according to data from the Centers for Disease Control and Prevention. More than 1,000 Americans die each day from the virus and nearly 80,000 are infected daily on average, according to data from Johns Hopkins University.The White House has told businesses to press ahead with implementing the requirements even as the legal drama plays out in the courts. Companies with 100 or more employees have until Jan. 4 to ensure their staff has received the shots required for full vaccination. After that date, unvaccinated employees must submit negative Covid tests weekly to enter the workplace. Unvaccinated employees must start wearing masks indoors at the workplace starting Dec. 5.The Biden administration faces a flurry of lawsuits seeking to overturn the mandates. Republican attorneys general in at least 26 states have challenged the requirements in five federal appellate courts. The cases will be consolidated in a single court through random selection among the jurisdictions where lawsuits have been filed. The Justice Department said earlier this week that it expects the random selection to take place on Tuesday at the earliest.David Vladeck, a professor of law at Georgetown University, told CNBC that there’s a “high probability” the case will ultimately end up in the Supreme Court, where there’s a conservative majority.”There are justices on the court who want to rein in the administrative state and this is a case in which those concerns are likely to come to the fore,” Vladeck told CNBC on Monday.