Date: Aug 21, 2026

Narrow Application of the “Miscarriage of Justice” Exception After Hunter: Within-Guidelines Sentences and Substantive-Reasonableness Claims Remain Barred by Knowing Appeal Waivers

1. Introduction

In United States v. John Cato (11th Cir. Aug. 18, 2026) (per curiam) (not for publication), the Eleventh Circuit dismissed a defendant’s appeal challenging the substantive reasonableness of a 180-month sentence for firearms trafficking under 18 U.S.C. § 933(a)(1) & (b). The government moved to dismiss based on a sentence-appeal waiver contained in Cato’s written plea agreement.

The central issues were (i) whether the waiver was knowing and voluntary and thus enforceable, and (ii) whether enforcing it would nonetheless create a “miscarriage of justice” under the Supreme Court’s recent articulation in Hunter v. United States.

2. Summary of the Opinion

The court enforced the appeal waiver and dismissed the appeal. It held that the district court specifically questioned Cato about the waiver during the plea colloquy, explained the waiver’s exceptions, and confirmed Cato understood and accepted the waiver’s terms. The court further held that Cato’s substantive-reasonableness argument fell squarely within the waiver and none of the enumerated exceptions applied (no above-guidelines sentence as calculated by the court, no sentence above the statutory maximum, and no government appeal).

Finally, the panel concluded that enforcing the waiver would not produce a miscarriage of justice because Cato did not demonstrate an “obvious” sentencing error; the district court imposed a within-guidelines sentence and reasonably explained its focus on the dangerousness of the offense conduct.

3. Analysis

A. Precedents Cited

King v. United States, 41 F.4th 1363 (11th Cir. 2022), abrogated in part on other grounds by Hunter v. United States, 146 S. Ct. 1702, 1710 n.2 (2026)
The panel relied on King for the governing framework: sentence appeal waivers are generally enforceable if entered knowingly and voluntarily, and waiver validity and scope are reviewed de novo. The abrogation note signaled that King remains operative for waiver principles except where Hunter altered the landscape.
Hunter v. United States, 146 S. Ct. 1702 (2026)
Hunter supplied the key limiting principle: even a knowing waiver will not be enforced when doing so would result in a “miscarriage of justice,” defined as leaving in place an egregious error that would bring the judicial system into disrepute. Critically, the majority described the requisite error as one that “must be obvious—not one a judge could reasonably make.” The panel used this “obvious error” threshold to reject Cato’s attempt to fit a substantive-reasonableness claim within the miscarriage-of-justice exception.

The opinion also referenced a concurrence in Hunter suggesting that a substantively unreasonable sentence might qualify as a miscarriage of justice. But the panel treated the concurrence as non-controlling and emphasized the majority’s stricter “obvious error” constraint.
United States v. Bushert, 997 F.2d 1343 (11th Cir. 1993)
Bushert provided the classic two-path test for enforcement: the government must show either (1) the district court specifically questioned the defendant about the waiver during the plea colloquy, or (2) the record makes manifestly clear that the defendant otherwise understood the full significance of the waiver. The panel found the first path satisfied.
United States v. Boyd, 975 F.3d 1185 (11th Cir. 2020)
Boyd sharpened the inquiry into a “touchstone”: whether it was clearly conveyed that the defendant was giving up the right to appeal under most circumstances. The panel treated the plea colloquy—where the district judge explained the waiver and each exception—as meeting that clarity requirement.
United States v. Bascomb, 451 F.3d 1292 (11th Cir. 2006)
Bascomb supplied the operational rule that knowing and voluntary appeal waivers are enforced “according to their terms.” Having found the waiver valid, the panel applied it as written.
United States v. Medlock, 12 F.3d 185 (11th Cir. 1994)
Medlock contributed a strong evidentiary presumption: statements made under oath in the plea colloquy are presumed true. This presumption supported the conclusion that Cato’s acknowledgments of understanding were reliable and binding.
United States v. Hardman, 778 F.3d 896 (11th Cir. 2014)
Hardman supplied interpretive methodology: plea agreement language is given its ordinary and natural meaning unless the parties indicate otherwise. The panel used this to place a substantive-reasonableness challenge comfortably within the waiver’s broad “any right to appeal” language, subject only to the specified exceptions.
Gall v. United States, 552 U.S. 38 (2007)
Gall appeared through the Hunter concurrence’s reference to the “deferential abuse-of-discretion standard” for sentencing review. The citation underscored why substantive-reasonableness claims—already highly deferential—rarely translate into the kind of “obvious” error required to pierce an appeal waiver after Hunter.
United States v. Butler, 39 F.4th 1349 (11th Cir. 2022)
Butler provided the sentencing-law baseline: district courts must consider the relevant factors, but the weight assigned to each factor is committed to their discretion, including the ability to give one factor great weight. The panel invoked this to conclude that the district court’s emphasis on the dangerousness of Cato’s conduct did not present an “obvious” error.

B. Legal Reasoning

Waiver validity (knowing and voluntary)
The court applied the Bushert/Boyd framework and found the waiver enforceable because the district court directly questioned Cato about the waiver during the change-of-plea hearing, explained that the plea agreement contained an appeal-waiver section, identified that there were exceptions, and then explained each of the three exceptions. Cato affirmed he had discussed the waiver with counsel, had no questions, and was voluntarily giving up appellate rights except as stated. Under Medlock, those sworn statements were presumed true.
Waiver scope (does it cover the issue raised?)
Cato raised only substantive unreasonableness. The waiver broadly covered “any right to appeal” the sentence, with three enumerated exceptions. Applying Hardman’s “ordinary and natural meaning” rule, the panel held the claim fell within the waiver. Factually, none of the exceptions applied: the sentence was within the advisory guideline range as calculated by the court; it did not exceed the statutory maximum described in the agreement; and the government did not appeal.
Miscarriage-of-justice safety valve
The opinion’s most important doctrinal move is its application of Hunter to substantive-reasonableness attacks in the presence of an appeal waiver. The panel acknowledged the Hunter concurrence’s suggestion that an extremely unreasonable sentence could qualify, but it treated the controlling standard as the Hunter majority’s requirement that the error be “obvious.”

Against that backdrop, the panel held Cato could not show an obvious error. It emphasized that the district court stayed within the guidelines range, considered both mitigating and aggravating factors, and reasonably focused on the “particularly dangerous” nature of Cato’s spree of selling guns and high-capacity magazines—an approach consistent with Butler’s recognition of wide discretion in weighting sentencing factors. Therefore, enforcing the waiver did not leave in place an error of the kind that would bring the judicial system into disrepute.

C. Impact

Although designated “NOT FOR PUBLICATION” (and thus limited in precedential effect), the decision illustrates how Eleventh Circuit panels may operationalize Hunter in routine plea-and-waiver cases:

Substantive-reasonableness claims will rarely defeat an appeal waiver absent truly unmistakable error. A within-guidelines sentence, accompanied by a record showing consideration of relevant factors, will be difficult to recast as “obvious” error under Hunter.
District-court colloquies remain the litigation fulcrum. The decision reinforces that detailed questioning and explanation of waiver terms and exceptions create a strong record for enforcement under Bushert and Boyd.
Concurrences provide arguments, not rules. The panel’s treatment of the Hunter concurrence signals that litigants must grapple with the majority’s “obvious error” threshold rather than rely on broader language from separate opinions.

4. Complex Concepts Simplified

Sentence appeal waiver: A contractual provision in a plea agreement where the defendant agrees not to appeal the sentence (often with narrow listed exceptions). If valid, it usually ends the appeal before the appellate court reaches the merits.
Knowing and voluntary: The defendant must understand what rights are being surrendered and must choose to surrender them without coercion. Courts test this during the plea colloquy under oath.
Plea colloquy: The in-court Q&A where the judge ensures the defendant understands the charge, penalties, rights being waived, and the plea agreement’s key terms (including appeal waivers).
Substantive reasonableness: A challenge arguing the sentence is too harsh (or too lenient) given the facts and sentencing purposes. Appellate review is deferential (as referenced via Gall v. United States), which makes “obvious” error hard to show.
Advisory guideline range: A recommended sentencing range calculated under the U.S. Sentencing Guidelines. A within-range sentence is not automatically lawful, but it often supports a finding that no clear error occurred.
Miscarriage of justice (post-Hunter): A narrow safety valve allowing courts to refuse enforcement of an appeal waiver when enforcement would cement an egregious and system-discrediting error—one that is “obvious,” not reasonably debatable.

5. Conclusion

United States v. John Cato reinforces a practical rule in the wake of Hunter v. United States: where the record shows a thorough plea colloquy and a clear, enumerated appeal waiver, an appellate court will enforce the waiver against a substantive-reasonableness challenge unless the defendant can identify an obvious, egregious sentencing error. The decision underscores the continued strength of appeal waivers in federal plea bargaining and the high bar defendants face in invoking the miscarriage-of-justice exception.