Executive branch does not have the authority to force congress, welfare, postal, etc., that’s the job of the legislative branch. Executive branch, Department of Labor, is issuing the mandate which is why it’s only affecting the employees of companies > 100.
Constitutional - Yes
The ability of the government to mandate vaccinations is a well-established constitutional authority. For instance, the Supreme Court ruled in Jacobson v. Massachusetts (1905) that a local school board’s vaccine mandate for smallpox was constitutional. The requirement for students to be vaccinated against certain diseases is also constitutionally valid, as solidified in Zucht v. King (1922). There’s no question that the government can require vaccines.
Grave Danger - courts will decide
The issue arises, however, in the manner by which the vaccine mandate is created. As part of the executive branch, the Department of Labor cannot simply create new laws (that’s Congress’s job). It can only enact regulations under existing laws and its authority established by Congress. For the Biden administration, this jurisdiction is found through the Occupational Safety and Health Act of 1970, which permits the Department of Labor to issue an “emergency temporary standard” for workplaces when employees are exposed to a “grave danger” from a “toxic or physically harmful” substance and the standard is “necessary to protect employees from such danger.”
Case for Vaccine
Almost 2 years into the pandemic. With an average of 1,800 deaths a day, something has to give. Companies are already using automation and offshoring to fill gaps and speed up restructuring plans during the pandemic. COVID have given companies a convenient excuse for subpar service while they make these changes. The longer this is prolongs the worse it will be for workers.