Originally Posted by ZirconBlue
I was referring to the 'crimes committed'
part of the previous statement.
In other words, a president can say "I pardon person X for shooting someone yesterday", but they can't say "I pardon person X for shooting someone tomorrow".
Ford's pardon of Nixon was for crimes that occurred previously. He didn't list specific crimes, but they were only for things that occurred in a previous, specific time frame.
(Now, you also mentioned the issue of 'convicted in the past', but since someone already brought up the issue of conviction, I assumed you were referring to the 'commission of crime')