Why the gun-totin' DA's petition was denied?

That I don't know.

Perhaps because the gun law has three exceptions to the prohibitions on carrying, and the law says "any" of them apply. In one exception, the law says a judge has the power to grant — or not grant — permission to conceal-carry licensees and in another exception the law says a DA can conceal-carry in court.

Because "any" of the exceptions apply, the judges chose the one that inconveniences the DA, and the judge has quite a bit more stroke in the courtroom than has the DA. For example a judge can tell a DA in her courtroom to sit down, be quiet, stop being such a dick, etc.

The Supreme Court wrote just a few months ago that a petition for a supervisory writ won't be accepted unless the lower court's duty is "plain" and the alleged violation by the subordinate court judge is "clear."

I don't think either of those elements are present here.

Furthermore if the court did accept this petition, it would potentially be in the position of having to contradict itself on the questions of supervisory and original jurisdiction — these are two separate grants of power to the court in the Wisconsin constitution and the Wisconsin statutes — for the third time in roughly one year.

What I find amusing is that the court combined these two separate grants of authority in its Act 10 decision in June, 2011, and a few months later laid down the law with respect to the high burden — the "clear" and the "plain" bits — of establishing its supervisory jurisdiction, which the "conservative" majority itself clearly had not done in the petition against Dane County Circuit Court Judge Maryann Sumi.

The attorney(s) who drafted this petition recognize the distinction between supervisory and original jurisdiction, hence the "or in the alternative" language and the separate references to 809.70 and 809.71 (the distinction between which was also discussed at this blog pursuant to some nonsense that was published at the Marquette Law School Faculty blog by a young Federalist Society pinhead).

More on all of that behind the links in the post [below].