What Trump could or could not do as president
He could do enough damage.
His signature issues are immigration and trade. He could not build the Mexican wall without congressional support. But he could order immigration authorities to deport unauthorized immigrants.
And he could bar Muslims from entering the country under existing law, which authorizes him to bar classes of aliens whose entry he determines “would be detrimental to the interests of the United States.” It wouldn’t be the first time: President Ronald Reagan cited this law, as well as his inherent constitutional powers, to block a flood of Haitian migrants from pouring into United States territory in 1981.
Can he slap tariffs on China, as he has threatened? Yes, he can. Congress has delegated to the president the power to retaliate against foreign countries that engage in unfair trade practices like dumping, leaving it to the president and trade officials to determine what that means…
In May, Mr. Trump vowed to rescind President Obama’s environmental policies. He would be able to do that as well. He could disavow the Paris climate change agreement, just as President Bush “unsigned” a treaty creating an international criminal court in 2002. He could choke off climate regulations that are in development and probably withdraw existing climate regulations. Even if a court blocked him, he could refuse to enforce the regulations, just as Mr. Obama refused to enforce immigration laws.
In wielding executive power in these ways, Mr. Trump would be following in the footsteps of his predecessors. President Bush cited his commander in chief powers in order to justify interrogation, surveillance and detention polices in the wake of Sept. 11…
He wouldn’t be able to put someone in jail merely for criticizing him. But he could direct agencies to use their vast regulatory powers against the companies of executives who have displeased him, like Jeff Bezos, for example, the founder of Amazon. Mr. Trump has already hinted that he would go after Amazon for supposed antitrust violations.
He could direct the Department of Justice to investigate his critics by prioritizing categories of crimes they may have committed. Political opponents could be accused of campaign finance law violations. Former government officials, like Hillary Clinton, could be accused of violating secrecy laws. Even if the charges come to nothing, the legal fees for defendants will be hefty.
Mr. Trump could also crack down on journalists who report on national security issues by enforcing federal secrecy laws more aggressively than previous presidents.