The proposals listed in the memo have either been enacted already or are in the process of being reviewed.
Here are four specific parts of the memos that several immigration experts say jumped out at them as cause for concern:
1. The possible change of designation for ‘unaccompanied minors’
"Exploitation of that policy led to abuses by many of the parents and legal guardians of those minors and has contributed to significant administrative delays in adjudications by immigration courts," the memo states, later noting that children can fall victim to kidnapping, extortion, robbery, sexual assault and other crimes of violence when handled by smugglers who are in some cases paid to help them cross the border.
2. The prospect of unaccompanied minors' parents being arrested
A related concern comes from the language that follows in the memo, where it states that any undocumented parents or relatives who try to reconnect with their children, who were unaccompanied when they crossed the border, could be either placed into "removal proceedings" or face criminal charges.
"We have an obligation to ensure that those who conspire to violate our immigration laws do not do so with impunity -- particularly in light of the unique vulnerabilities of alien children who are smuggled or trafficked into the United States," the memo reads.
Woltjen told ABC News that such threats could have an immediate effect.
"The consequence of that is that many parents will be afraid to come forward and sponsor their children out of fear that they'll be charged criminally, arrested, or put in jail," she said.
"I would argue that they're not trafficking their own children. They want their children to be safe. It's what any parent would want their children to do," Woltjen said, referencing the violence that has spread in many of the noncontiguous countries, prompting parents to get their children out of those areas.
"To charge these parents with criminal activity for doing what any parent would do is just wrong and contrary to what this country has stood for," she said.
3. Mass hiring of thousands of agents and officers
The first memo states that Customs and Border Patrol will hire 5,000 new agents and 500 air and marine agents and officers, and the second memo – titled “Enforcement of the Immigration Laws to Serve the National Interest” – notes that Immigration and Customs Enforcement will hire 10,000 new agents and officers as well as support and legal staff.
"That in itself is not a civil liberties violation but we think it's very likely that ... because you'd be bringing on so many people so quickly, that there would be a real risk that they could not be trained properly," the ACLU’s Gelernt told ABC News
“If you're going to bring on 15,000 new agents, in a short span of time, it seems almost inevitable that the training will suffer and also the vetting process for who you hire,” he said.
4. Deputizing law enforcement
Such a policy concerns immigrant rights supporters like Enrique Morones, the executive director and founder of the nonprofit Border Angels, who said it will lead to immigrants’ being suspicious of law enforcement and a reluctance to come forward or work with officers in other situations.
"The police acting as immigration agents is not a healthy situation," Morones told ABC News.
Lisa Koop, the associate director of legal services at the National Immigration Justice Center, said she and her colleagues have already heard similar concerns on the ground.
"We're hearing from our clients of really increased anxiety and fear about being arrested, for example, when they go and pick up their children from school or just in the course of their daily lives, basically," Koop told ABC News.
This provision "has the potential to make them fearful of local law enforcement,” she said. “That's not good for our communities."
Trump has not address these specific concerns but White House press secretary Sean Spicer said Tuesday said mass deportation is not the goal.
“The message from this White House and from the DHS is that those people who are in this country and pose a threat to our public safety or have committed a crime will be the first to go and we will be aggressively making sure that that occurs,” he said. “That is what the priority is.”
Editor’s note: The interview with Maria Woltjen, executive director of the Young Center for Immigrant Children’s Rights in Chicago, has been updated.