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Google, Microsoft and Facebook are among more than 100 tech companies banding together to mount a legal challenge to President Donald Trump's effort to end DACA.

The companies filed a brief Wednesday in support of Deferred Action for Childhood Arrivals, or DACA, which offers protection to undocumented immigrants who came to the US as children, sometimes referred to as Dreamers. The Trump administration said in September it would end the Obama-era program, which lets immigrants brought to the US illegally as children before 2007 stay without fear of deportation.

"DACA has produced -- and is continuing to produce -- important benefits for America's companies and for our economy as a whole," the companies wrote in the brief (PDF). "Employment is not a zero sum game. Dreamers are filling vacancies at companies that cannot find enough workers to fill their needs."

Apple, which filed its own brief opposing the move, said the company employs more than 250 Dreamers in 28 states.

"These talented and entrepreneurial people fill important and varied roles across the company, including in operations, research and development, administration, sales and marketing, and retail," Apple's VP of People Deirdre O'Brien wrote in the brief, seen by Axios. "Apple and its customers have benefitted greatly from their intelligence, ambition, creativity, resilience, and hard work.

"These employees are important contributors to Apple's unique culture. That unique culture enables employees throughout Apple to do the best work of their lives and excel at creating the most innovative products and providing the very best customer service," O'Brien wrote.

The legal briefs are just the latest salvo in tech companies' opposition to Trump's move, which could affect as many as 800,000 Dreamers. In September, Apple CEO Tim Cook, Amazon CEO Jeff Bezos, Google CEO Sundar Pichai and more than 300 others -- signed a group letter addressed to Trump, urging him to reconsider the move.

For years, the tech community has pushed for immigration-friendly policies. Traditionally, its biggest concern has been for policies supporting immigration of skilled workers, people that American tech companies say they need to keep their competitive edge.

As early as 2013, executives such as Facebook CEO Mark Zuckerberg spoke out about protecting the legal status of Dreamers. He said he was inspired to take up this issue while tutoring undocumented students. In 2013, he started the FWD.us group to lobby for pro-immigration policies and broad immigration reform.

Opponents to Trump's move cite the basic economic sense of not wanting to increase the unemployment level, which could have real consequences for tech companies always on the lookout for talent.

A study by the Center for American Progress estimated that the loss of all DACA workers would reduce US gross domestic product by $433 billion over the next 10 years.

The White House didn't immediately respond to a request for comment.

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