Or for more specific examples, given, Gore v Bush, when exactly does the court have standing to intervene in a presidential election? Given DC v. Heller in 2008, what does the word "militia" mean now? Why, to everyone's surprise, did maritime law suddenly limit punitive damages with Exxon vs Baker (2008)? Why did the court narrowly reverse 200 years of convention and the near universal understating of speech with Citizens United?
Moreover, allow me to remind you that Citizens United is actually a nonprofit group+ and the thing this case was actually about was making an anti-Hilary movie, and being barred from distributing it. Anyone who has glanced at the Bill of Rights, and the history of this nation and its jurisprudence in the area of free speech, could have seen this result coming. (Somehow there are many people not aware of this fact.)
(+ not a charity, contributions aren't tax deductible; just a standard 504 not-for-profit.)
This may or may not be good policy. It's eminently open to debate. But hewing to precedent like this is supposed to be your evidence of the Court acting on a whim?!?
Because of this, it is utterly uninteresting to observe the peak of government power, like compelling the draft. The draft is specifically legally authorized in the Constitution, in which the Government is lawfully granted the power to raise and support Armies. It can do so while obeying the law. This is not "the whims of the courts," and the courts are barely involved, because the law is so very clear.
Quarantine powers are also subject to the power of law, including both general police powers and Constitutionally protected rights. When these conflict, there are a variety of legal tests to determine which wins, and there is legal precedent for interpreting the laws. When the courts interpret this conflict, it will almost certainly not be on a whim.