They don't even need EO's. it doesn't come from that high up the chain.
Just some lawyer at ATF decides they can get away with a "change of policy".
That is the problem with
Regulatory Agencies". they circumvent the power of Congress to make the laws by saying it isn't a "law", it's just agency policy.
And that is set by some lawyer who was never elected, or vetted by any one.
#1 would be Eric Holder, but can you pardon before trial, conviction and sentencing?
Yes, Nixon was never charged, tried, or convicted of anything. Ford pardoned him for everything he did or may have done.
One thing though.
Obama can pardon everyone, except himself.