As we reluctantly educate ourselves about presidential pardons, we should keep in mind the limits of Trump's power to pardon. He may pardon his family, friends, courtiers, and other enablers, and, perhaps, himself, but there are real limits to his power.

First, as previously explained here, the presidential pardon power applies only to federal crimes. State law-enforcement officials (attorneys general and county prosecutors, usually), acting under State criminal laws, may prosecute
actors for conduct that is criminalized under State law, even if that exact same conduct, by the exact same actors, has been presidentially pardoned under federal law.

For example, under the "dual sovereignty doctrine," a homicide might be a federal hate crime and a state-law homicide. The perpetrator of the hate-crime could be presidentially pardoned, so that the crime could not be prosecuted under federal criminal civil-rights statutes, but the homicide could still be prosecuted as an ordinary murder under state law.

Second, as discussed in my earlier article, a president might not be able to pardon himself or herself, though no one can answer this question conclusively because it's never been tried.

The debate on this "might not" question is very robust. My own views on this have shifted back and forth, especially in light of an excellent, albeit brief, analysis published here. There is a good summary of constitutional experts' opinions here. Opinion among the experts, however, is divided on the lawfulness of the presidential self-pardon.

Third, it's been argued here and elsewhere that Trump could pardon himself for his criminal conduct up to the time of his self-pardon, but the pardon itself might be a crime for which he could not pardon himself.

One final thing might give him pause: A self-pardon might itself be a crime: By analogy, if a president agreed to veto legislation in exchange for a bribe, the veto would be valid, but the bribe would be a felony. Depending on the circumstances, a self-pardon might similarly be valid in its function as a pardon but felonious as an obstruction of justice. Since a pardon can only cover past actions, moreover, a criminal self-pardon could not cover itself. A president might still find it worthwhile to trade a raft of criminal charges for a single count of obstruction of justice. But this adds one more item to the list of reasons not to self-pardon.

In other words, if Trump pardoned himself for the specific purpose of obstructing justice, the pardon might not protect him from prosecution for the obstruction of justice accomplished by the pardon. And if he pardoned himself a second time for his obstruction-of-justice-by-pardon, the second pardon - and any subsequent pardon for the pardon - might still be a prosecutable obstruction of justice.

(This reminds me of the old joke about the wise man who said the world was carried on the backs of turtles. When asked what carried the turtles, he said, "It's turtles all the way down." We might face a similar situation of serial presidential pardons for earlier criminal pardons. How many pardons? "It's pardons all the way down.")

Fourth, pardons can be granted to business entities, as well as individual persons, but even if they can receive presidential pardons, it is more difficult for these entities to withhold information entirely from investigations. See for, example, Michael Flynn's agreement to produce some business documents after he personally invoked the Fifth Amendment.