The environment for patent overhaul has been shaped by changes in politics and public attitudes, as well as the rising number of patent suits. In December 2013, the House overwhelmingly passed legislation aimed at curbing patent litigation. A key provision in the bill, written by Bob Goodlatte, a Virginia Republican and chairman of the House Judiciary Committee, was to make the losing party pay legal fees. The provision was an attempt to increase the cost and risk for plaintiffs, deterring trolls from bringing many suits in what amounts to legal prospecting for a big payday.

In the Senate last year, Harry Reid, the Nevada Democrat who was then majority leader, said he would not bring patent legislation to a vote. Trial lawyers, who as a group are large campaign contributors to the Democratic Party, strenuously objected to the fee-shifting provision in the proposals. Mr. Reid’s decision was widely interpreted as a nod to the trial lawyers’ lobby.

After last year’s election, the Republicans are the majority in the Senate as well as the House, adjusting political calculations somewhat.

Still, the Obama administration and many Democrats are now champions of patent overhaul to curb the flood of patent suits. The Senate bill, written mainly by Charles E. Schumer, a New York Democrat, and John Cornyn, a Texas Republican, would place restraints on demand letters, essentially threats to settle or be sued; require information on who actually owns a patent, making it more difficult to hide behind “shell” companies; and require losing parties to pay legal fees if the court decides the suit was not “objectively reasonable,” a deterrent to frivolous suits.

The fee-shifting provision in the Senate bill, for example, is a case of modifying the House proposal. The House bill would require the loser to pay unless the court made an exception. Under the Senate bill, fee-shifting is not the “presumptive” starting point, its sponsors say, but will only be done if the court determines the suit to be unreasonable.