New York Attorney General Eric Schneiderman is out again with another reminder that he doesn't like the way high-frequency traders operate. He believes they have unfair advantages, and that it's a bad idea for stock exchanges to sell them special services that cater to their wants. For that matter, so do I. So on that we can agree.
But Schneiderman also says there's something about these arrangements that might be illegal, without saying what it is. If that's true, he ought to spell it out. Instead, he's back to his old ways of threatening to investigate companies and maybe sue them for fraud unless they change their practices in a way that he deems acceptable. No matter how noble his intentions, this isn't how a law-enforcement officer should operate.