A couple weeks ago, after House Speaker Paul Ryan called members to order, he had this reminder to share: "Members should wear appropriate business during all sittings of the House, however brief their appearance on the floor may be," he said.

As it turns out, though, that rule has been just about always been around. It just hasn’t really been enforced — until recently.

Last week, CBS News reported that a female reporter was turned away from a guarded room known as the Speaker’s Lobby, a common spot for reporters to talk to lawmakers, because she was wearing a sleeveless dress. Men have been given what one reporter called on Twitter a “tie of shame” if they leave theirs at home.

This has created a bit of a stir. So what exactly does this rule require?

Well, that’s unclear. There’s no dress code enforced on the Senate side of the aisle, and there’s nothing really codified in this rule, just a sort of general expectation that you should wear "appropriate attire.”

But that is something that Washington Post fashion critic Robin Givhan says is not as simple as it sounds these days.