[Maxatar]

Just to clarify, a pardon in the ordinary sense can't be refused. If you're imprisoned and the President pardon's you, you can't decide to refuse the pardon and remain in prison. As soon as the pardon is granted you are released, whether you like it or not, whether you "accept" it or not.

The Burdick case had to do with an individual who had not yet been convicted of anything being offered a pardon in exchange for testimony that could have otherwise incriminated him. The Supreme Court ruled that in that specific scenario someone accepting a pardon could be seen as admitting guilt, so the pardon couldn't be forced on Burdick to strip away his fifth amendment right and compel his testimony.