United States v. Peter Sepling, 944 F.3d 138

Peter Sepling pled guilty under a Rule 11(c)(1)(C) agreement to importing GBL and was released on bond pending sentencing.
While on bond he became involved in a methylone conspiracy; prosecutors agreed to factor methylone conduct into Sepling’s GBL sentence as relevant conduct rather than bring new charges.
The PSR analogized methylone to MDMA and used the Guidelines’ 500:1 MDMA-to-marijuana conversion, producing a Guidelines range of 188–235 months (base level 32); counsel only contested weight, not the 500:1 ratio.
At sentencing counsel admitted ignorance about methylone/MDMA and relied on Sepling’s lay testimony that methylone was a “watered down ecstasy”; no expert or independent research was presented.
The district court imposed 102 months after a downward variance; Sepling filed a §2255 ineffective-assistance claim, which the district court denied; Sepling appealed.
The Third Circuit vacated and remanded, holding counsel’s failure to investigate the substance analogue and 500:1 ratio was constitutionally deficient and prejudicial under Strickland.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether sentencing counsel was ineffective for failing to investigate methylone/MDMA and challenge the 500:1 conversion ratio	Sepling: counsel failed to reasonably investigate a central sentencing issue and thus performed deficiently	Government: sentence reflected §3553(a) factors and counsel secured a substantial downward variance; claim is frivolous	Held: counsel was deficient for not investigating methylone/MDMA or challenging the analogue/ratio
Whether Sepling was prejudiced by counsel’s failures despite receiving a below-Guidelines sentence	Sepling: lack of meaningful advocacy undermines confidence in outcome; better evidence likely would have produced a larger variance	Government: district court relied on §3553(a), not the Guidelines, so no prejudice from Guideline flaws	Held: prejudice shown — court was “flying blind”; reasonable probability of a lesser sentence if counsel had presented available evidence
Whether counsel was ineffective for advising Sepling he had no appealable issues	Sepling: counsel’s advice was additional ineffective assistance	Government: not contested as central here	Held: Court did not need to reach this claim because ineffective assistance at sentencing was established

Strickland v. Washington, 466 U.S. 668 (1984) (two‑prong ineffective‑assistance test)
Glover v. United States, 531 U.S. 198 (2001) (any amount of jail time has Sixth Amendment significance)
Booker v. United States, 543 U.S. 220 (2005) (Guidelines are advisory)
Gall v. United States, 552 U.S. 38 (2007) (district court must correctly calculate applicable Guidelines range)
Rompilla v. Beard, 545 U.S. 374 (2005) (failure to investigate mitigating evidence at sentencing can be ineffective assistance)
Molina‑Martinez v. United States, 136 S. Ct. 1338 (2016) (incorrect higher Guidelines range can show reasonable probability of different outcome)
Peugh v. United States, 569 U.S. 530 (2013) (Guidelines anchor sentencing decisions)
Kimbrough v. United States, 552 U.S. 85 (2007) (district courts may vary based on policy disagreement with Guidelines)
United States v. Kamper, 748 F.3d 728 (6th Cir. 2014) (district courts may reject MDMA‑to‑marijuana ratio)
United States v. Gray, 878 F.2d 702 (3d Cir. 1989) (failure to investigate can show ineffectiveness)
United States v. Jenkins, 333 F.3d 151 (3d Cir. 2003) (plenary review standard for Strickland issues)
United States v. Headley, 923 F.2d 1079 (3d Cir. 1991) (remand for district court consideration after finding counsel ineffective)