A proffer agreement, sometimes referred to as a “queen for a day” letter, is a written agreement between federal prosecutors and individuals under criminal investigation which permits these individuals to give the government information about crimes with some protection against prosecution.
Before concluding a cooperation agreement or bestowing immunity upon a criminal defendant, federal prosecutors typically necessitate that the individual “proffers” or presents the details that they will offer in return for more lenient treatment. According to Federal Rule of Evidence 410 and Federal Rule of Criminal Procedure 11(f), declarations made during plea negotiations with the government are, in most instances, not permissible as evidence.
Proffer agreements outline the rights and responsibilities of involved parties, including the prosecution’s right to utilize the defendant’s declarations or the defendant’s duty to maintain honesty. While these agreements can serve as safeguards for the defendant’s rights, they can also provide the prosecution with an upper hand they always have during plea negotiations.