A group of women alleging sexual violence from Uber drivers have sent an open letter to the company’s board, asking to be released from the mandatory arbitration clause in the Uber app’s terms of service. The letter was posted on the website of Wigdor LLP, a New York law firm that filed a class action lawsuit against Uber last year on behalf of women who said they were assaulted or raped by Uber drivers and blame the company’s background check procedures.

“Uber’s message to the public are: ‘we help improve access to transportation, and make streets safer’ [and] ‘We do the right thing, period,’” read part of the letter, which was signed by fourteen women. “Secret arbitration is the opposite of transparency. Forcing female riders, as a condition of using Uber’s app, to pursue claims of sexual assault and rape in secret arbitration proceedings does not ‘make streets safer.’ Silencing our stories deprives customers and potential investors from the knowledge that our horrific experiences are part of a widespread problem at Uber.”

They added “when we created Uber accounts, we believed Uber’s promise to provide a ‘safe ride.’ We trusted a company operating in the space of transportation for hire to mean what it says, and we never thought that Uber would perpetuate physical violence against women. But this is exactly what Uber is doing and what is has been doing for years.”

Once a relatively obscure legal issue, mandatory arbitration agreements are now under scrutiny by activists who say they force victims of harassment and discrimination into silence. Opponents of mandatory arbitration say that the closed hearings, which include non-disclosure clauses and are often performed by a third-party arbitrator paid by the company itself, prevent victims from taking further action even as social movements like #MeToo continue to gain ground.

Many companies require employees to sign mandatory arbitration agreements as a condition of employment. According to the Economic Policy Institute, the number of non-union, private sector employees covered by mandatory arbitration clauses has increased dramatically since the early 2000s.

Wigdor LLP noted that some companies, like Microsoft, are ending forced arbitration clauses, especially for sexual harassment, while a bipartisan bill has been introduced in the United States Congress that would end forced arbitration of sexual harassment cases in workplaces, and called on Uber to follow suit.

In an exchange last month with former Uber engineer Susan Fowler on Twitter, Dara Khosrowshahi, who succeeded Travis Kalanick as Uber’s chief executive officer last August, signaled that he is willing to consider ending forced arbitration. “I will take it seriously, but we have to take all of our constituents into consideration,” he wrote.

Fowler, whose blog post detailing sexual harassment at the company led to an internal investigation and contributed to the resignation of Kalanick, is now backing a new bill in California that would forbid companies from forcing employees to enter mandatory arbitration agreements in response to sexual harassment and other workplace discrimination complaints.

TechCrunch has contacted Uber for comment.