We like to think we have rule of law, but in practice that is a fairly flimsy concept that ultimately depends on how many people in power are willing to adhere to it. Something could be against the law, the Supreme Court could rule that it’s against the law, (although with all the right wingers they stacked the court with, even that’s not gonna happen often.) the legislature could object, but at the end of the day, if the executive instructs the government workers to do something and they’re willing to do it, well… they can do it. So the politics of those government workers ultimately determines what can and can’t be done. And since those workers are downstream of appointments made by the executive… they’re likely to agree with them. And we see that bear out especially in the military and law enforcement agencies. The culture of these institutions is fairly right wing and the people in them have demonstrated a willingness to follow illegal orders and commit some truly heinous acts, even if they rationalize it as “just following orders.”

It’s not just under Trump either. The government has been acting in ways that violate our own laws for a long time. Every war we’ve been in since WWII has been an illegal act since they were never formally declared as wars and many of the things done in them have violated various international humanitarian laws. Police have straight up killed people without trial and were protected by their fellow officers and the government. And of course now we see ICE agents be more than willing to commit crimes to pursue this anti-immigrant agenda, whether they are just following along or they’re also ideologically committed to this.

So yeah. The answer can be anything as long as he find enough amoral right wingers or pushovers to staff the administration.