SpaceX and Amazon are among the companies that have filed lawsuits challenging the constitutionality of the National Labor Relations Board. NASA/Joseph Prezioso/Getty Images hide caption toggle caption NASA/Joseph Prezioso/Getty Images In the nearly four years that Joe Biden has been president, the National Labor Relations Board has taken an assertive — some say overly aggressive — approach to protecting workers' rights to organize and collectively bargain. Now, SpaceX and Amazon are at the fo...