Yesterday, President Trump made a speech applauded by law enforcement encouraging their rough treatment of suspects, specifically including a removal of protection from physical injury when a suspect is being loaded into a police vehicle for transportation. The context of the speech indicated that the rough treatment should be especially applied on the basis of perceived national origin.
If some career prosecutor in the Department of Justice didn't or doesn't "get the memo" against investigation and prosecution of federal civil rights violations by police, could an officer accused of this violation successfully claim that this speech (and/or others like it) contained a presidential pardon?
It seems clear that no conviction needs exist at the time of the pardon nor does the specific crime need to be identified (e.g. Ford's blanket pardon of Nixon), nor does the specific individual being pardoned have to be identified (e.g. Carter's pardoning of draft dodgers), and that official pronouncements from this President do not necessarily come in formally structured executive orders (e.g. Tweeted ban on transgender military service). These factors suggest the answer may be "yes," but I am not familiar with the actual requirements of what it takes to make a pardon valid.