"Acceptance, as well as delivery, of a pardon is essential to its validity; if rejected by the person to whom it is tendered, the court has no power to force it on him. [...]
There are substantial differences between legislative immunity and a pardon; the latter carries an imputation of guilt and acceptance of a confession of it [...].
The facts, which involve the effect of a pardon of the President of the United States tendered to one who has not been convicted of a crime nor admitted the commission thereof, and also the necessity of acceptance of a pardon in order to make it effective are stated in the opinion."
- Burduck v. United States, 236 US 79 (1915), Supreme Court of the United States, internal citations and quotes omitted.
There are substantial differences between legislative immunity and a pardon; the latter carries an imputation of guilt and acceptance of a confession of it [...].
The facts, which involve the effect of a pardon of the President of the United States tendered to one who has not been convicted of a crime nor admitted the commission thereof, and also the necessity of acceptance of a pardon in order to make it effective are stated in the opinion."
- Burduck v. United States, 236 US 79 (1915), Supreme Court of the United States, internal citations and quotes omitted.
https://supreme.justia.com/cases/federal/us/236/79/case.html