When activist Lau Barrios saw that 250 Microsoft employees had called for their company to cancel its police contracts and support defunding the Seattle police department, she says she felt "extremely hopeful."

But it's unclear if much will come of the effort.

Nationwide protests over the killing of George Floyd have spurred a reckoning within the tech industry over race and ethics, prompting companies like IBM and Snap to make significant policy changes. But history shows that Microsoft has rarely heeded the demands of employees and activists pushing for structural change within the company, particularly when it comes to Microsoft's lucrative law enforcement and defense contracts.

Since OneZero published a letter Monday, addressed to CEO Satya Nadell and signed by 250 employees, Microsoft has not responded publicly. A Microsoft spokesperson declined to comment further and pointed Protocol to CEO Satya Nadella's blog post from last week standing against racial injustice.

Here's a rundown on previous protests against Microsoft and how the company responded.

• Microsoft's work with ICE: In June 2018, hundreds of Microsoft employees signed an open letter protesting the company's work with Immigration and Customs Enforcement. Ultimately, the company did not walk back its multimillion-dollar contracts with ICE, which stand today. Andy Ratto, a volunteer with immigration group Close the Camps NYC who helped plan the Microsoft protest, said "it remains an ongoing concern and an ongoing effort to try and continue to pressure Microsoft around this issue."

• GitHub's work with ICE: Microsoft also faced pressure over its ICE ties since acquiring GitHub, the world's largest host of source code, in 2018. After it came to light that GitHub maintained a $200,000 contract with the agency, multiple GitHub employees resigned, Microsoft employees posted an open letter on GitHub in solidarity with the protests, and over 2,000 open-source contributors penned an open letter asking GitHub to cancel its contract and commit to higher ethical standards. GitHub CEO Nat Friedman defended the contract and did not address the grassroots protests. "They never said anything," said Daniel Sieradski, who helped organize the GitHub efforts.

• JEDI contract: In October 2018, Microsoft announced its intent to bid for a $10 billion cloud computing contract with the Department of Defense — the famous JEDI deal. Soon after, an anonymous group of Microsoft employees published a Medium blog titled "An Open Letter to Microsoft: Don't Bid on the US Military's Project JEDI." Last year, Microsoft won the $10 billion deal over Amazon Web Services, a surprise to analysts who had predicted AWS was most likely to win. AWS has since been contesting the award of the contract.

• HoloLens: A group of more than 100 Microsoft employees signed on to a letter in February 2019 protesting the company's plan to equip the U.S. military with up to 100,000 augmented reality headsets called HoloLens. But Nadella defended the $479 million contract with the Pentagon in an interview, saying the company will not "withhold technology from institutions that we have elected in democracies."

• AnyVision: For months last year, groups including MPower Change and Jewish Voices for Peace pressured Microsoft to stop funding an Israeli startup called AnyVision, which was surveilling Palestinians in the West Bank. A petition from the groups gathered more than 75,000 signatures, and the activists partnered with Microsoft workers to deliver the petition to Microsoft's Redmond campus. In March of this year, Microsoft announced it was divesting from the company — one of most high-profile instances of Microsoft taking action in response to protests. "When activists and media and workers [are] all on the same page, you can win," said Granate Kim, an organizer with Jewish Voices for Peace who worked extensively on the campaign. A turning point, says Kim: when a Microsoft employee spoke up against AnyVision during a company town hall.

Now, with Microsoft's partnerships with police departments across the country well-known, the question is: Is this time any different? Will the company continue to provide law enforcement with cloud computing power, facial recognition technology and various forms of surveillance technology, or listen to the complaints of some of its staff?

Barrios, who helped organize the protests around AnyVision, said she thinks it's "important" that Microsoft workers are following the lead of Black organizers in the movement. "If you're in solidarity with Black Lives Matter, that means you have to follow the demands of it," she said. "Your actions have to speak louder than your PR statements." And this time, it finds itself under new pressure on some fronts: around its facial recognition business, for instance, after rival IBM announced it will no longer sell facial recognition technology due to the human rights and ethics concerns.

"Microsoft execs did a great job to 'listen' long enough for the energy to go away when Microsoft workers asked for the ICE contracts to get canceled," tweeted tech industry activist William Fitzgerald. "Let's hope this time around workers keep pushing until these contracts actually get canceled."