There was a strange moment at the Board of Supervisors today that shows just how powerful even the discredited law-enforcement lobby can be.

The supes were considering a resolution endorsing a bill by Sup. Mark Leno that would mandate more police accountability. These things are usually pretty routine, and get put at the end of the meeting: It’s rare that any resolution supporting a measure by one of our local representatives gets anything but unanimous support.

Scott Wiener wants to clear out homeless tents
Scott Wiener sides with the cops and against Sen. Mark Leno’s accountability measure

But that wasn’t the case today – and the supe who tried to derail the resolution was Scott Wiener, who has been a close Leno ally and whom Leno has endorsed to replace him in the state Senate.

I was surprised when I was first reporting on this that Wiener wasn’t among the supes who had signed onto the endorsement resolution. The Leno measure is more than reasonable, and it has the backing of dozens of major civil-rights and open-government groups.

But the SF Police Officers Association and the statewide law-enforcement lobby are fighting it. I texted Wiener and asked him whether he was with Leno on this one, and he said:

“I have concerns about the legislation in its current form, but I am open to supporting it in a more targeted form, focusing on sustained complaints of extreme use of force or egregious misconduct.”

At the meeting, he said that he thinks the measure will be amended eventually (that is, watered down). “This bill, in its current form, I won’t be able to support it today.”

Again: Huh? Leno has done so much for Wiener, helped him get elected supervisor, helped him with his state Senate campaign, and there are very few times I can remember when Wiener hasn’t supported something Leno was doing.

In this case, it’s a really important measure that would have an impact on the rash of police misconduct. As Sup. David Campos noted, “this is actually a pretty mild piece of legislation.”

But Wiener couldn’t bring himself to support the bill. So instead, he tried a parliamentary trick: He asked that the supes resolution be divided into two measures, one that simply commended Leno for taking on the issue, and another that actually endorsed the bill.

That way he could vote to comment Leno and say he was open to some sort of police reform – but still not endorse the actual measure that Leno was trying to pass.

Any member of the board has the right to divide a piece of legislation, so there was no debate on it.

Instead, Sups. David Campos and Aaron Peskin argued against the pointless commendation, which went down 8-3 with only Wiener, Mark Farrell, and Katy Tang voting yes.

The actual measure endorsing police accountability passed by the same measure, with the same vote.

So Wiener in effect tried to undermine a key piece of legislation his mentor and ally is working hard to pass, against sustained law-enforcement opposition. This, I suspect, will be an issue in the state Senate campaign.