At least four policy proposals floated by Donald Trump during the course of his campaign would provoke major legal challenges if he attempted to implement them as president, constitutional scholars at the American Civil Liberties Union have concluded.

A series of legal memos released by the ACLU on Thursday raise serious questions about the constitutionality of Trump's plans to deport the 11 million illegal immigrants currently living in the U.S., surveil mosques, bar non-American Muslims from entering the country and relax libel laws.

"By our analysis, a Trump administration would violate the First, Fourth and Eighth Amendments if it tried to implement many of his most controversial policies," ACLU executive director Anthony Romero told reporters during a conference call Wednesday evening.

Romero said Trump's "mass deportation scheme" would violate the Fourth Amendment prohibition of unreasonable searches and seizures and the equal protection clause of the 14th Amendment since "immigration officers would have to inevitably resort to racial and ethnic profiling to carry out" the deportations.

Shortly after the Orlando, Fla., shooting in June, Trump doubled down on his calls for surveilling mosques in the U.S., telling voters in Atlanta that "we have to go and we have to maybe check, respectfully, the mosques."

"If Mr. Trump becomes president and begins to either convince Congress or act unilaterally to implement a surveillance program on Muslims, he would likely face challenges from us and from other advocates based on the equal protection clause of the laws under the Fifth Amendment of the Constitution," said Romero.

The ACLU director also rejected Trump's consideration of a registry for Muslim-Americans, saying it would violate the Fifth Amendment due process clause. Trump has never given an affirmative answer as to whether or not he would seek to implement such a database as president.

According to Romero, the presumptive Republican presidential nominee must also be careful in his suggestion that the U.S. "open up our libel laws so that when they [reporters] write purposefully negative and horrible and false articles, we can sue them and win lots of money."

"The Constitution imposes a very high barrier for libel suits brought by public officials," he noted, adding that Trump's "idea of opening up libel laws is further fraught because it begins to still the importance of public discourse precisely when it is most needed."

"As we look across all these different positions ... we think that Mr. Trump's policies would engender a legal and constitutional battle in federal courts, but also in the Supreme Court that is unseen among modern day presidents," Romero told reporters.

The ACLU, which Romero defended as "staunchly nonpartisan," is planning to release similar legal reports about policies put forward by Hillary Clinton in the coming weeks.

"Secretary Clinton's positions have changed and evolved a great deal over time, but there are a number of areas where we are deeply troubled," Romero told the Washington Examiner.

He said ACLU staffers are "more than halfway done" with their analysis of Clinton's immigration proposals and statements she's made about torture, in addition to other areas of concern.