Trevor Burrus offers a simple — but important — question that each prospective nominee to the U.S. Supreme Court should be forced to answer. The Heritage Foundation’s “Insider Online” highlights Burrus’ analysis.

What’s something you think is a good idea but you think is unconstitutional? Or, conversely, what’s something you think is a bad idea but you think is constitutional?

Everyone concerned with the Constitution — and most especially Supreme Court nominees — should be asked this question. And if they don’t have an answer — that is, if they think everything they like is constitutional — then maybe they don’t really believe in the Constitution.

In many ways, this question defines modern debates over the Supreme Court, and, supposing whoever President Obama nominates makes it to the Senate Judiciary Committee, it will also define the debate over the late Justice Antonin Scalia’s replacement.

The question is crucial because it helps delineate the difference between a judge and a legislator, at least in theory. Legislators get to always vote their preferences; judges, however, don’t. …

… To Justice Scalia, as well as many of his fellow conservatives on the bench, to be a judge was to strive to eliminate his policy preferences from his decision making as much as possible. As he once said, “If you’re going to be a good and faithful judge, you have to resign yourself to the fact that you’re not always going to like the conclusions you reach. If you like them all the time, you’re probably doing something wrong.”

Full disclosure: I am an originalist, and I was, and am, a big fan of Justice Scalia. Nevertheless, I often profoundly disagreed with his views, particularly on gay marriage. Yet, even in his vituperative dissents in the gay marriage cases, there was still a sense that Scalia was imploring us to detach our personal opinions about same-sex marriage from the question of whether there is a right to it in the Constitution.