Reports are that this is one option being considered by the presdient in the face of the Russia investigation.
Could he do this? There is no precedent for it, but the Constitution does confer upon the president broad powers to pardon. Here is the relevant text from Article 2 section 2 – the president has the power
‘to grant reprieves and pardons for offences against the United States, except in cases of impeachment,’”
The only express limit on the president’s power is that it does not apply to impeachment. Some argue that the absence of a limit would mean Trump could pardon anyone, including himself, whether charged or not with a crime. Precedent suggests that Trump could preemptively pardon his family and staff and anyone else. If he attempted to pardon himself, that matter could go to the US Supreme Court for an interpretation of Article 2, Section 2. If it does, keep in imind that the absence of text would not prohinit the Court form reading text into the clause in order for it to make sense.
So, for example, would the absence of this sort of limit put th president above the law? There is precedent that the presiden tis not above the law (for example, the Nixon case, and the decidsion that litigation against President Clinton could proceed while he was in office). On the other hand, the Supreme Court could find that even if the president pardoning himself endangers the rule of law, impeachment is the only remedy.
Moreover, any action by Trump to pardon anyone could constitute in itself an obstruction of justice. That is an impeachable offense and Trump has no powers to stop impeachment based on that.
Will this happen? It is too early to tell. But the fact that the president is considering these options shows how seriously he takes Muelle’s investigation. That is not the attitude one would expect of an innocent bystander. Moreover, pressuring and then firing Jim Comey already may have been obstruction of justice. The open question would be whether it was done with the intention to obstruct. The fact that Trump is considering further impediments to this investigation adds to the sense that obstruction was and is his main intention.
I leave open the obvious question whether Republicans in Congress would take steps to impeach under the above circumstances.
BTW, here is an interesting wrinkle to this area of the law. In order for a pardon to be effective, the pardoned person must accept it. Accepting a pardon constitutes an admission of guilt. My own guess is that Trump himself would not admit guilt, except in the most dire circomstances. If soo, we may see a full court press to quash Mueller’s investigation first, and an orgy of pardoning later, as needed and possible, if that effort fails.