How are we going to stop them, other than with a democratic process of constitutional amendment?
Two points. First, I suggest a re-read of Marbury v. Madison. Marshall refused to exercise judicial power, because the court was not granted the power (by the Constitution) to grant the remedy that the plaintiff sued for. The phrase "to determine what the law is" can be taken in two diametrically opposite ways. The vast majority of cites to Marbury v. Madison interpret the phrase the worng way, i.e., that the court makes the law.
Stopping runaway judges? That's hard, but either that happens, or this experiment we call the USA will not be durable. Go ahead, amend the Constitution. But what are the people going to do if the judges ignore that? See, e.g., the Campaign Finance Reform law that prohibits the purchase or sale of candidate-pointed television or radio advertisement in the 60 days before an election. Is it Constitutional in light of the 1st amendment ("Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press ...")? Well, is it Constitutional? The answer is YES, because 1) it was passed by congress, 2) signed by the President and 3) SCOTUS ruled that it is.
The Court refused to issue a writ of mandamus because they decided SCOTUS did not have jurisdiction, under the Constitution, in the case. OK, so far so good, looks like they were exercising restraint.
But wait: Jurisdiction in the case had been awarded to them when Congress passed the Judiciary Act of 1789 -- so the Court, in refusing this jurisdiction granted by an act of Congress, invalidated an act of Congress!
In doing so, the Supreme Court established a precedent that the Court could declare acts of the other two branches of government unconstitutional. This was not a power explicitly outlined in the Constitution.
That's what I remember learning about it, anyway. And that's why I see it as a power-grab. Tell me where I'm wrong.