When a contentious bill to expand Chicago’s O’Hare International Airport came to the House floor last year under a procedure normally reserved for handling noncontroversial measures, Rep. Henry Hyde (R-Ill.) wondered why.

“I do not know about others, but I love a mystery; and this bill is as mysterious as anything Agatha Christie ever wrote,” Hyde said on the House floor. “First of all, why is such a controversial bill being brought under suspension? What a mystery. Why are the bill’s proponents, and I almost said perpetrators, allergic to debate and amendments?”

Although he lost the fight that day after two-thirds of the House voted to approve the bill, Hyde and others immersed in the legislative process may be even more astonished at a little-noticed but remarkable trend: The vast majority of bills enacted into law are now initially considered under the seemingly mysterious suspension process, which provides for just 40 minutes of debate, no amendments and requires a two-thirds majority for passage.

Indeed, statistics show the suspension trend reached its high point in the 107th Congress, when eight out of every 10 bills enacted into law were brought to the House floor under the procedure. Two decades ago, roughly a third of enacted laws were brought to the House floor under the same process.

So, why is a procedure that by its very nature requires a high degree of bipartisanship flourishing in a House that is increasingly polarized and divided along party lines? The answer may be that the suspension process has turned into a sort of safety valve, effectively letting off legislative steam while allowing the House leadership to maintain tight control over the process of lawmaking with restrictive rules that curtail amendments and debate.

In a paper presented last year to the American Political Science Association, Don Wolfensberger, who served as chief of staff for the House Rules Committee from 1995 to 1996, studied the history of the suspension procedure and theorized about its increasing use.

Wolfensberger, who now directs the Congress Project for the Woodrow Wilson Center for International Scholars, argued that “as fewer amendments are being allowed on the House floor to major bills, the majority leadership is compensating by allowing for the consideration of more noncontroversial bills, sponsored by more members, under the suspension of the rules procedure as a means of partially satisfying members’ needs for reelection, public policy influence, and power in the House.”

Most of the bills considered under suspension are barely noticed by the press and deal with the mundane and low-key matters of post office names, land transfers, water projects and public works initiatives.

In the process of governing the House with restrictive rules that limit the ability of individual lawmakers to shape legislation and test public policy choices, the suspension process gives the leadership a way to placate lawmakers who might otherwise rebel against a closed process. Wolfensberger calls it a way “to keep peace in the family.” Bills brought to the floor under the suspension process are generally aimed at specific constituent interests or regional needs and serve to bolster the re-election needs of individual lawmakers.

“The suspension bridge is a convenient structure for leaders to achieve their party maintenance responsibilities,” Wolfensberger said. “It allows leaders to re-route some members’ re-election and policy needs away from major bills. This in turn relieves the leaders of some of the congestion and pressures that swirl around their attempts to fashion strategies and procedures necessary to passing important legislation.

“Taken together, the two processes, suspensions and restrictive rules, serve the needs and goals of party members and leaders alike,” Wolfensberger said.

“The availability of a convenient outlet for members to call up noncontroversial legislation having strong bipartisan support serves as a safety valve and trade-off for leaders in retaining party loyalty in support of restrictive, special rules for more important, controversial, and partisan legislation,” Wolfensberger concluded.

Traditionally, suspension matters have been considered in the House on Mondays and Tuesdays, days when lawmakers are often still in transit from their districts or fundraising events. But the GOP leadership this year included a provision in the opening-day rules package that allows suspension procedures to be used on Wednesdays until mid-April. Democrats criticized the change as a way of institutionalizing an even shorter Congressional workweek because presumably the House won’t be in session on Mondays.

“Democrats believe that far too many bills are considered under suspension already and that the House is thus denied the opportunity to fully debate and amend legislation,” said Rep. Martin Frost (D-Texas), the ranking member on the Rules Committee. Frost argued unsuccessfully that the Republican leadership should bring up fewer bills under suspension instead of more bills. “There is ample time in our calendar to spend on the floor debating legislation. We should not be institutionalizing shortened weekdays and cutting off debate,” he said.

But complaining about the suspension process isn’t unique to Democrats. When Republicans were the minority party, abuse of the suspension process was often cited in indictments against the Democratic majority.

In 1975, a House GOP task force on reform noted that, “The more the suspension procedure is used, the more it is abused, to the detriment of sound legislative practice and results.”

The origin of the suspension procedure can be traced to the early days of Congress in 1794, when the House allowed motions to suspend its rules with one day’s advance notice. In 1822, the provision was changed to require a two-thirds majority, but the procedure was used mostly as a tool to control the scheduling of bills, not their adoption.

All that changed in 1868 during the House consideration of the impeachment of President Andrew Johnson, when a parliamentary ruling established the ability to suspend House rules and adopt a measure with a single vote.

A motion was offered by Rep. Elihu Washburne (R-Ill.) to suspend the rules and adopt, not just consider, a set of procedures for debating the impeachment of Johnson. A point of order was raised against the motion on grounds that the House had a right to vote separately on the two propositions — suspending the rules and adopting the impeachment procedures. Speaker Schuyler Colfax (R-Ind.) overruled the point of order and thereby established the precedent for the dual purpose motion to suspend the rules and pass a measure by a single vote.

While the suspension procedure was often abused by lawmakers seeking to buck their leaders, the process gradually came under control through the Speaker as a method for quickly handling noncontroversial matters. The Monday and Tuesday suspension tradition came into being in 1977 and the Democratic Caucus adopted additional safeguards for the process in 1979.

When the GOP took the reins of power in 1995, the Republican Conference adopted similar rules for handling suspension matters. Requests to consider a bill under suspension must be made in writing to the Speaker and be accompanied by a cost estimate of the legislation. The request also needs to state that the measure has been cleared by the ranking minority member and is not opposed by more than one-third of the committee members who reported it.

In addition to bills intended to become law, Wolfensberger found that the number of resolutions and concurrent resolutions considered under the suspension process is also increasing. And the leadership sometimes uses the process to score political points even though the measures fail to get the two-thirds majority needed for passage.

On Feb. 6, 2002, the leadership scheduled a nonstatutory, concurrent resolution introduced the day before by Rep. Spencer Bachus (R-Ala.) under suspension that expressed the “sense of the House of Representatives that the scheduled tax relief provided for by the Economic Growth and Tax Relief Reconciliation Act of 2001 passed by a bipartisan majority in Congress should not be suspended or repealed.”

The measure fell 43 votes short of the two-thirds vote necessary, 235 to 181, but managed to peel off 26 Democrats in support while losing just one Republican. This, Wolfensberger noted, allowed Republicans to make their point and drive a wedge into Democratic ranks.