Below are a few links on this topic. Due process applies to "all persons" within the US, which would include non-citizens. That does
not mean that non-citizens have all the same rights that citizens have. I don't think anyone is claiming that. But at the very least, from a legal and constitutional standpoint, they have due process.
"It is well-established that everyone within the United States, even those who may have entered illegally or over-stayed a visa, are entitled to Due Process."
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"Thus, despite the President’s tweet, a robust system exists to protect the due process rights of people, even non-citizens, in the United States, and federal courts, under a long line of Supreme Court cases, are tasked with the job of making sure it will always be so."
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The Trump administration and its supporters have long labored under the false notion that non-citizens do not have full legal rights under the US constitution. In this, they reflect the views of Dick Cheney and other politicians of the era of the “Global War on Terror” when the executive state was forever searching for new ways to justify spying on American citizens and expanding the police state.
This idea, however, has no grounding in text of the Bill of Rights or in the thinking of American “founders”...
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"The Court reasoned that aliens physically present in the United States, regardless of their legal status, are recognized as persons guaranteed due process of law by the Fifth and Fourteenth Amendments."
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