When they told the federal government to fuck off when they wanted to permanently deputies state leos to enforce federal gun background checks first springs to mind. there have been others, like Roberts upholding "the Muslim ban," but the thing that I still grudgingly respect him for is that he refused in Sibelius to extend the commerce clause into mandating market participation. this is essentially the same principle that's at stake with the vaccine mandate, but even worse because here there's no economic activity, just a noneconomic activity that if you apply the shitty Wickard v Fillburn rule, can in the aggregate substantially affect economic activity.
that would likely be the approach the DOJs taking (again I haven't read it yet), and if Roberts takes the bait any idea that he has legal principles and a guiding philosophy is over