This educational guide is based on the linked primary sources. It is not a Court publication, is not affiliated with the Court, and is not legal advice.
In brief
Overview
According to United States, united States v. Alphonso Vonn is a criminal case concerning the validity of a guilty plea entered without proper advisement of the right to assistance of counsel under Rule 11(c)(3).
According to Government, the case also raises the question of whether errors in the plea colloquy are reviewed under the harmless error doctrine (Rule 11(h)) or the plain error rule (Rule 52(b)).
According to United States, the appellate court set aside the guilty plea, finding the district court failed to advise the right to assistance of counsel as required by Rule 11(c)(3).
Background and question before the Court
According to United States, respondent Alphonso Vonn pleaded guilty with counsel present after being advised of his right to assistance of counsel at all stages of the proceedings.
According to Defendant, the defendant denied that he personally possessed a gun or had knowledge of co‑defendants possessing guns.
The central legal question is whether the failure to advise the right to assistance of counsel during the plea colloquy constitutes a reversible error subject to harmless error review or plain error review.
What each side argues
United States (Petitioner)
According to United States, the appellate court erred in setting aside the guilty plea; the district court's failure to advise the right to assistance of counsel under Rule 11(c)(3) should not automatically reverse the conviction.
According to Government, the drafters of the rule intended to negate a prior holding that suggested automatic reversal for a Rule 11 violation.
According to Government, there is a general presumption that preserved errors are reviewed under the harmless error doctrine (Rule 11(h)), while errors not preserved at trial are reviewed under the plain error rule (Rule 52(b)).
Alphonso Vonn (Respondent)
Source-limited. The record does not yet support a complete account.
What happened at oral argument
According to Justice, qUESTION: But the cleanest way to negate it would be to simply say, you engage in some kind of an analysis of consequences. You either do it in terms of harmless error or you do it in terms of plain error.
According to Justice, qUESTION: Why?
What the Court decided
Why it matters
According to Government, the distinction between harmless error review and plain error review determines whether a procedural mistake can be corrected on appeal, affecting defendants' rights.
Terms to know
No glossary terms are available for this guide.
Primary sources
Read the source materials on the official site or open the immutable repository copy used for this guide.
- e063724b979ba75d1ec8-r1-5d7b378961710d3d.pdforal argument transcript
Guide generated September 19, 2026. Automated validation accepted this version.