WASHINGTON  Supreme Court confirmation hearings are usually designed to probe a nominee’s conception of the role of the justices. But this week’s questioning of Elena Kagan turned into a tutorial on Congressional responsibility.

Over and over, Ms. Kagan reminded the senators questioning her of their own duty to pass cogent, sensible  and constitutional  laws. The Supreme Court, she said, was not created to strike down foolish measures.

On Tuesday, for instance, Senator Tom Coburn, Republican of Oklahoma, asked what should happen if Congress enacted a law requiring Americans “to eat three vegetables and three fruits every day.”

“It sounds like a dumb law,” Ms. Kagan said. But she would not commit to striking it down. “I think that courts would be wrong to strike down laws that they think are senseless, just because they’re senseless,” she said.