What's the biggest difference between the letter about patent trolls that prominent VCs sent to Congress in 2013 and the letter (PDF) they sent out today? Four times as many names.

In total, 140 investors in startup companies have signed a letter to Congress asking them to implement changes to patent laws that have been debated for more than two years now. The move looks to keep one important fact front-and-center: "patent trolls," companies in the business of suing over patents, aren't just a plague for tech giants—they are a huge problem for medium- and small-sized companies as well.

"When a troll sues, or even threatens, a small startup, the results can be disastrous," the letter states. "Many of us have seen young companies fail in the face of such threats."

Among venture capital investors, 70 percent say their portfolio companies have been hit with patent threats, mostly from trolls. It's a situation which the letter calls "not sustainable." The letter continues:

Our Constitution favored a patent system to incentivize innovation and benefit all Americans. Unfortunately that system has been hijacked by some intent on exploiting Patent Office weakness, and all too frequently it now hinders innovation and chills investment, harming the new companies it was designed to foster and imposing a patent troll tax on new technologies.

The letter asks for patent reform legislation that includes provisions for easier fee-shifting, protections for end users of technology, limits on the scope of discovery, and increased transparency requirements. Under such circumstances, the group hopes patent owners would have to include more information in any lawsuits or demand letters they might send.

Engine, a lobbying group that works on behalf of startups, estimates that 55 percent of troll lawsuits are filed against startups with revenues of less than $10 million. With the cost of seeing through a patent lawsuit ranging between $1 million and $5 million, sometimes fighting back isn't an option.

The last Congress debated a bill called the Innovation Act, which would have made many of the changes the letter specifies. The bill passed the House with a strong majority but got stopped in the Senate. With new leaders in the Senate, reformers are hopeful they'll have a second chance this year, and a 2015 version of the Innovation Act has already been introduced.

Some of the better-known investors on the list include Ron Conway of SV Angel; Steve Case of Revolution; Fred Wilson of Union Square Ventures; Brad Feld of Foundry Group; and Jessica Livingston of Y Combinator.