Believe it or not, the prosecution and defense occasionally agree (more or less) on the facts underlying criminal charges. Plea bargains regularly arise from these scenarios. But sometimes the parties agree on what happened, agree on the parameters for punishment, yet can't agree on whether a conviction is appropriate.
A conditional plea occurs when the defendant pleads guilty or no contest but reserves the right to have an appeals court decide whether the judge reached the wrong ruling on an issue that's central to the case. If the appellate court determines that the judge was in fact wrong, the defendant can withdraw the plea.
Conditional pleas are available in federal court and in many states. Typically, though, the prosecution and the judge must agree to them. (The agreement with the prosecution may have to be in writing.) The defendant may be able to enter a conditional plea of "no contest," or the law might require that the plea be "guilty."
If the law in the state in question doesn't allow for conditional pleas or the prosecution or court won't agree to one, the options are limited. If the defendant insists on reserving an issue for appeal and refuses to enter a plea free of conditions, the judge may have to enter a "not guilty" plea on his or her behalf.
On the other hand, defendants sometimes have a right to appeal certain rulings even if their pleas weren't conditional. For instance, in a few states, defendants, despite having pleaded guilty, automatically may appeal denials of motions to suppress. Defendants can, however, lose that kind of right to appeal by waiving it as a condition of a plea deal.
Regardless of the state, appeals may be possible in other kinds of plea-bargain situations—where, for example, there was ineffective assistance of counsel.
An appeal after a guilty plea can also be possible where the defense is arguing that a law violates the Constitution. The U.S. Supreme Court has held that a guilty plea, standing alone, isn't enough to stop a federal criminal defendant from appealing a conviction on the grounds that the law in question is unconstitutional. In the case leading to the holding, one of the defendant's claims had been that the statute creating the crime he was convicted of was unconstitutional. He argued that 40 USC § 5104(e)'s "Possession of a Firearm on U.S. Capitol Grounds" violated the Second Amendment. (Class v. U.S., 583 U. S. ____ (2018).
The written plea agreement in the case didn't say the defendant couldn't directly appeal on these kinds of grounds. The plea "colloquy" left a little more room for interpretation, but the Court found that the defendant neither "expressly nor implicitly" waived his right to the constitutional challenge.
If a defendant would have appealed after being convicted of a crime but lost the chance to do so because of the defense attorney's "constitutionally deficient performance," the defendant received ineffective assistance of counsel. That ineffective assistance entitles the defendant to an appeal—even if the defendant earlier signed a plea agreement with language waiving the right to appeal (what courts refer to as an "appeal waiver").
The U.S. Supreme Court stated these rules in the case of Garza v. Idaho, where the defense lawyer disregarded the defendant's requests that the lawyer file a notice of appeal. (A notice of appeal is a first step in an appeal; it often comes before the defense even knows exactly which arguments it will make in the appeal.) (586 U.S. ___ (2019).)
In the Garza case, the Supreme Court found that the lawyer was wrong to fail to file the notice of appeal even though the defendant had signed appeal waivers in his two plea agreements. The Court noted that the ultimate decision of whether to appeal isn't the lawyer's, but rather the client's. And it confirmed that appeal waivers don't always actually waive the right to appeal.
The specific language of the appeal waiver matters—some waivers forfeit more possible appeal claims than others. And among the other reasons appeal waivers aren't absolute is the fact that defendants don't lose the right to challenge whether the waiver itself was "knowing and voluntary." (Generally, for a waiver to be "knowing and voluntary," the defendant has to understand its consequences.)
If you face criminal charges or want to know whether you can appeal your case, talk to an experienced criminal defense lawyer. This article doesn't cover close to all the possible grounds for an appeal. An experienced attorney should be able to fully advise you of the law, the procedure, and your options.