The Senate filibuster is actually created by the lack of rules in debate. “When a Senator desires to speak, he shall rise and address the Presiding Officer, and shall not proceed until he is recognized, and the Presiding Officer shall recognize the Senator who shall first address him,” states paragraph 1(a) of Rule XIX. “No Senator shall interrupt another Senator in debate without his consent, and to obtain such consent he shall first address the Presiding Officer, and no Senator shall speak more than twice upon any one question in debate on the same legislative day without leave of the Senate, which shall be determined without debate.”
The filibustering senator must remain standing and “must speak more or less continuously,” according to the Congressional Research Service. Even when yielding for a question, Paul had to keep standing. Paul also noted that he wasn’t prepared for the filibuster but jumped in when he saw the floor was open — the majority leader obviously will try to structure the daily schedule to disallow for a minority filibuster if he knows one is in the works. Paul was able to sneak in because Harry Reid (D-Nev.) neglected to file for cloture on the Brennan nomination Wednesday morning.
Eating is not allowed on the Senate floor, which is why Paul was furtively sneaking bites of candy and an apple Sen. Mark Kirk (R-Ill.) brought for his colleague was removed from his desk by the sergeant-at-arms. Ironically, Kirk is the keeper of the “candy desk” — the old desk of Sen. George Murphy (R-Calif.) who, in the 1960s, began stashing sweets in his desk for his colleagues. Kirk keeps the desk stocked with candy made in his home state, including Jelly Belly, Milky Way, and Mars bars.
The Pastore rule requires that debate be germane, but it’s usually not enforced especially as a senator tries to maintain a filibuster. No matter, though, as Paul stuck to the topic, even as some of the senators who asked questions wandered off point.
Exceptions to the Senate rules in times of filibuster would have to receive consent from the presiding officer, and the majority doesn’t want to make it easy for the minority. If, for example, a senator confined to a wheelchair wanted to filibuster and needed to circumvent the standing-only rule, the majority would find itself running afoul of the ADA if it didn’t provide reasonable accommodation.