While Amazon CEO Jeff Bezos was throwing a lavish party at his $23 million mansion in Washington, DC, this weekend—attended by celebrities like Ivanka Trump and Bill Gates—hundreds of his employees were gearing up to revolt.

At issue was the company’s external communications policy and reports earlier this month that it threatened to fire employees for speaking out about climate change without proper authorization. In protest, more than 350 Amazon workers published statements under their own names in a Medium post on Sunday, intentionally violating the policy en masse.

The protest was organized by Amazon Employees for Climate Justice, a coalition of activist workers that has pushed for the company to adopt more environmentally friendly policies over the past year. The group organized a climate change walkout last fall that was attended by thousands of Amazon and other tech workers around the globe.

“Corporations cannot own the conversation that threatens our very existence,” wrote Maren Costa, a principal user experience designer at Amazon. “We can’t be silent about issues that harm our children, communities, and planet.” Costa is one of several employees who were told they could be fired if they continued speaking publicly about Amazon without getting advanced approval. In the fall, Costa spoke with several news outlets, including WIRED, about what she said was the company’s inadequate response to the climate crisis.

LEARN MORE The WIRED Guide to Climate Change

Amazon has long required employees to get approval before speaking publicly, but the policy wasn’t strictly enforced, according to The Washington Post. In September, right before the walkout, Amazon created a new internal portal for workers to request permission to speak with the press; employees are now required to have a “business justification” for doing so.

None of the workers who contributed to Sunday’s Medium post appear to have used that formal channel. “The idea is to intentionally break the communications policy so prolifically that it is unenforceable,” Amazon Employees for Climate Justice wrote in an email sent internally last week to collect statements and signatures; it later made the message public.

Many large companies have policies about external communications, and AECJ acknowledged that Amazon’s policy makes sense in some cases, such as confidential projects. “But allowing a corporation to silence us on its contribution to the climate crisis is a clear overreach of comms policy, and effectively demands we give up our basic humanity and integrity in order to be employees,” the group wrote in its message.

“While all employees are welcome to engage constructively with any of the many teams inside Amazon that work on sustainability and other topics, we do enforce our external communications policy and will not allow employees to publicly disparage or misrepresent the company or the hard work of their colleagues who are developing solutions to these hard problems,” an Amazon spokesperson said in a statement. The spokesperson did not comment on whether Amazon would take action in response to Sunday’s post.

The statements the group published Sunday addressed a range of issues beyond Amazon’s impact on the environment. The Medium post is a laundry list of controversies the company has weathered in recent years, including labor issues, safety and privacy, and political influence, among others.

Not all of the statements were critical of Amazon’s outside communications policy. One worker said it prohibited her from sharing positive opinions with the press. “I want to be able to speak to the media about all the innovative things we ARE doing to protect Alexa customer privacy,” wrote Emily Greene, a software engineer. “I work every day to improve our protections of customer data, and it’s disappointing when the media spins the truth because the people who speak up are the ones with nothing to lose.”

A number of Amazon employees who participated in Sunday’s Medium post commended the company’s recent environmental efforts. Ahead of the walkout in September, Bezos unveiled a new “Climate Pledge,” where businesses promise to regularly disclose greenhouse gas emissions and reach carbon neutrality by 2040. Amazon was the first company to join. “I am proud to work at Amazon and to be working on such an important topic. I feel supported by our company and by our leadership to make this our top priority,” wrote Kimberly Pousman, an engagement manager working on the Climate Pledge.