The attached paper was co-authored by R Street Governance Project Director Kevin Kosar.


At the start of the 114th Congress, newly minted Senate Majority Leader Mitch McConnell, R-Ky., announced he was returning the chamber to “regular order.” While the phrase “regular order” is ambiguous, McConnell made clear his new approach would end the contentious practice of “filling the tree,” wherein the majority leader blocks meddlesome amendments from the floor by stacking the available slots with his own amendments. The strategy of filling the tree had been attacked both within and outside the chamber as an undemocratic restriction on the rights and duties of individual senators. McConnell and his fellow Republicans, then in the minority, highlighted former Majority Leader Harry Reid’s use of the technique in their 2014 campaign, suggesting it was the primary cause of the legislative inefficiency that plagued the chamber.

For their part, Reid, D-Nev., and his Democratic colleagues had argued that individual senators were abusing their rights, offering divisive, irrelevant amendments purely for electoral purposes. In their view, filling the tree was a necessary tactic to increase legislative efficiency. For example, Sen. Angus King, I-Maine, quoted a senator up for re-election during a Democratic caucus meeting: “‘I don’t mind making hard votes, but not if the Republicans are going to turn around and filibuster the bill anyway, so it’s all for naught.'” Sen. Saxby Chambliss, R-Ga., conceded:

“It’s pretty easy for us to put the blame on Harry Reid…. But the fact of the matter is, too, that we have some folks who are bound and determined to come up with some wild and crazy amendments that are intended to be purely political amendments rather than doing the business we were sent here to do in a very serious way.”

Just a month into the new Congress, the Senate already had voted on more amendments under McConnell’s leadership than in all of 2014 under Reid. However, members from both parties have criticized McConnell for violating his open-amendment-process pledge at times. Recent episodes suggest he may be unable to maintain it.

McConnell allowed an open-amendment process on the Keystone Pipeline bill, the first major piece of legislation considered in the 114th Senate. In response, senators filed nearly 300 amendments to the bill on a disparate range of issues, from climate change to endangered species and private-property rights. Negotiations and a successful cloture motion reduced the number of amendments granted floor consideration by more than 80 percent. In March 2015, House and Senate Republicans criticized McConnell for filling the amendment tree to ensure a vote on a “clean” funding bill for the Department of Homeland Security. In June, after suffering what was dubbed his “biggest legislative defeat” of the Congress, members of both parties criticized the majority leader for barring amendments to the USA Freedom Act. The decision led Sen. Rand Paul, R-Ky., refused to consent to vote on cloture, causing a one-day lapse in certain provisions of the PATRIOT Act.

The debate over the process of filling the amendment tree highlights an ever-present tension in Congress between members’ individual rights and legislative efficiency. Are floor amendments best characterized as helpful attempts by individuals to improve legislation? Or are they simply electoral tools to highlight differences between members and their partisan or ideological opponents?

The answer, certainly, is both. But our data demonstrate the ratio is changing. Specifically, preliminary evidence from a new dataset of 29,860 amendments filed and offered to approximately 497 landmark legislative enactments from the 45th Congress (1877-1878) through the 111th Congress (2009-2010) reveals the number of amendments offered has leapt. Additionally, more amendments are being offered by senators in the minority party, leading majority leaders to block them. Thus, absent internal reforms to discourage senators from offering contentious amendments, majority leaders will continue to “fill the tree” and make use of other amendment-barring maneuvers.