D.C. Court of Appeals Allows Second Amendment Challenges to Handgun Ban Conviction

The case is Magnus v. U.S.

Magnus argued that "his guilty pleas were invalid because he was misinformed of what the government would have to prove in order to convict him, constitutionally, of the charged crimes."

Magnus was able to withdraw his guilty plea 14 years later under coram nobis. The reason for this ability was stated quite well by the Court:

If, as in Bousley, the defendant is under the mistaken impression that non-criminal conduct is criminal because "neither he, nor his counsel, nor the court correctly understood the essential elements of the crime with which he was charged" – as those elements are clarified by later judicial decisions – then the defendant's guilty plea is unintelligent and "constitutionally invalid."

And here's my favorite tidbit from the opinion:

A conviction for conduct that is not criminal, but is instead constitutionally-protected, is the ultimate miscarriage of justice.

It doesn't get any more well-stated than that.