The president has no business undermining the judiciary in the first place.

Although I do find it strange that there is no check on the judiciary.

Like, it’s supposed to be checks and balances, but what stops the judges from passing an unjust law?

Judges have a lifetime appointment in the Supreme Court. The only way they can be removed is by all of Congress coming together and choosing to impeach one of them, and that takes years when Congress is actually functioning.

Judges don’t pass law at all. At must jurisprudence in the absence of law. Laws are the realm of the legislative.

The legislative could pass a law limiting supreme court term to 16 years tomorrow of they wanted.

Judges don’t pass laws, but they can create plenty of loopholes out of thin air. Qualified Immunity doesn’t exist in any statute (to my knowledge), but it is a de facto legal standard, for one example.