James Wallner writes at the Library of Law and Liberty:
"Look behind every major legislative success the U.S. Senate has had in recent years and you will find a small group of senators who negotiated quietly in private. Working under the supervision of party leaders, these groups are tasked by the collective, explicitly or implicitly, with resolving difficult issues, writing legislation, and helping to structure the process by which the Senate considers important bills.
"They resemble scrums in rugby. They are highly competitive, also decisive (eventually), and also opaque to anyone outside of them—which happens to be most everybody.
"The Oxford English Dictionary defines a rugby scrum as a formation used to restart play. Once one has taken shape, a ball is tossed into the middle. The other players on the field watching their teammates struggle over it have no direct knowledge of what is happening inside the scrum. Eventually, the ball emerges, at which point it is picked up by a player who charges down the field toward the other team’s goal line.
"Instead of competing over a ball, the members of a senatorial scrum are crafting legislative proposals that can make it through the chamber largely unchanged. And just like the non-participating rugby players who hang back from the action, waiting for the ball to come out, the other senators try to discern what is happening from the outside, waiting for an agreement to emerge so that they can cast their votes.
"Senatorial scrums are useful in dealing with controversial issues in the context of must-pass legislation. But this has distracted from the fact that their regular use undermines the Senate’s deliberative function. Making decisions in this way inevitably limits the policy ideas given serious consideration to those supported by the scrum’s members. Importantly, it entails a floor process (by which the full Senate considers compromise agreements) that is structured so as to obstruct other members from amending the bill. Restricting the policies considered in this way makes it more likely that the bill will not be fully vetted before it is signed into law."