While every criminal defendant has a right to an appeal, the right to appeal may be waived. Many government attorneys insist upon a waiver of the right to appeal pursuant to a plea agreement under which the defendant pleads guilty in exchange for some promises or concessions from the government. Waivers of the right to appeal are enforceable if they are voluntary and knowing. The Federal Rules of Criminal Procedure require a court to specifically advise the defendant that he is waiving his right to appeal at the time he pleads guilty.