Bangladesh, Sept. 2 -- New Yorks attorney general is supposed to be the states chief law-enforcement officer, not the political enforcer for one party or the personal adversary of one president.

That distinction matters enormously in a democracy. Prosecutors possess extraordinary powers: they can investigate individuals, compel documents, bring lawsuits, negotiate settlements, and potentially put people and companies under enormous financial and reputational pressure. Those powers are legitimate only when exercised according to law and evidence-not political loyalty.

That is why the allegations contained in a recent email from New York Assistant Attorney General Daniel Wiesenfeld deserve serious scrutiny.

According to reports by the Al...