Are there precedents for Congresspersons going in uninvited to closed-doors committee proceedings?
While there seems to be no list of such actions, here is one incident.
[Congressional Record Volume 150, Number 77 (Friday, June 4, 2004)]
[Extensions of Remarks]
From the Congressional Record Online through the Government Publishing Office
DEMOCRACY ON DRUGS, p E1039
When the House and Senate each passed their own version of the Medicare bill, the Republican leadership at first followed routine procedure by appointing a 17-member conference committee to work out the differences between the two pieces of legislation. Seven Democrats were appointed to the committee. However, only two of those Democrats, Senators Max Baucus (MT) and John Breaux (LA), were included in the closed-door meetings that had actually produced the final legislation. Why? Because they were among the few Democrats who would not raise significant objections to the bill. According to conference members from both parties, when the bill was made available to the rest of the committee, they were given just one hour to review the 678-page document before they voted.
The ranking Democrat on the Ways and Means Committee, Rep. Charles Rangel (NY), was among the members of the original conference committee. However, he was excluded from the closed-door meetings. He arrived uninvited to one meeting, and Rep. Thomas, the conference chairman, stopped substantive discussion of the legislation until Rep. Rangel left.
Democrats and others have complained the tactics like those employed during the conference on the Medicare bill are becoming more common. Similar lockouts were staged during crucial conference committee meetings on huge energy and transportation bills. More and more the role of the full conference committee is perfunctory while the details of the legislation are hammered out in closed meetings that include only a small coterie handpicked by the party leadership.