Question: When is something you place on your head a hat?

Answer: When the guy holding the gavel says so.

When Rep. Bobby Rush (D-Ill.) donned a hoodie sweatshirt on the House floor Wednesday, in a show of solidarity with slain Florida teen Treyvon Martin, the chair called him to order. “The chairman must remind members of clause five of rule 17,” said Rep. Gregg Harper (R-Miss.), who was presiding over the floor when Rush made his sartorial protest. “The member is out of order!”

But the rule that Harper invoked--contained in the section of House rules governing decorum--bans the wearing of hats on the House floor. That meant that House leaders thought his hooded sweatshirt constituted a hat.

Kind of a stretch, we’d say. If anything that sits on one’s head is a hat, why wasn’t Rep. Jim Traficant’s legendary toupee barred from the floor? The ban on hats dates back to the 1800’s, House staffers tell us, and it’s recently been challenged, to no avail, by Rep. Frederica Wilson (D-Fla.), who has petitioned leaders for a rule change to allow her to wear her signature chapeaus in the chamber.

But if Harper wanted to call Rush out for crimes of fashion, he probably would have been on safer ground if he had stuck to the language in the “Speaker’s Announced Policies,” which mandates “appropriate business attire” on the House floor.

That standard, set in the days of House Speaker Tip O’Neill, is typically interpreted to mean coats and ties for gents. For the ladies, the lines are harder to draw--and women in the chamber even sport open-toed sandals, sleeveless tops, and the like.

Later, House Speaker John Boehner issued a more general reminder about appropriate floor attire. “You know who you are,” he added.