As our Monday editorial explains, there are several problems with President Trump’s highly objectionable pardon of former sheriff Joseph Arpaio. I want to address a couple of them in more depth — one here and one in a subsequent column.

The latter will deal with abuse of the pardon power. It dovetails with arguments I’ve made about the “obstruction” aspect of the Mueller investigation — specifically regarding how our constitutional design counters a president’s abuse of prosecutorial-discretion powers (of which, I contend, the pardon power is one).

For now, I want to home in on the decidedly unpresidential impulsiveness of the pardon. I happen to believe Arpaio, formerly the top lawman in Maricopa County, Ariz., was a very undeserving pardon candidate. But even if one believed he was a fitting candidate, pardoning him at this stage was rash.

Arpaio’s conviction is not even final yet. A judge just found him guilty on July 31. In federal criminal procedure, a judgment of conviction is not entered when a guilty verdict is announced. There is no formal conviction until a sentence is imposed. Arpaio was not scheduled to be sentenced until October. In the interim, his defense was entitled to file post-trial motions attacking the verdict and seeking a new trial.