United States v. Potter, 2022 DNH 80

On May 31, 2021, Officer Nicholas Kapteyn stopped a gray Volkswagen Jetta on northbound Hooksett Road after observing it "move left" after the dotted lane line ended without the driver using a turn signal. The roadway at that point gradually narrows from two lanes into one (the "narrowing point").
Kapteyn did not observe a discrete lane change or crossing of the dotted line; he believed the driver violated RSA 265:45 (signal requirement) and initiated the stop.
Potter, a passenger, initially gave a false name, was later identified and found to have outstanding warrants; he was arrested and his bag was searched, yielding suspected narcotics and leading to federal drug charges.
Potter moved to suppress the evidence, arguing the stop violated the Fourth Amendment because RSA 265:45 did not require signaling when a roadway itself narrows/merges and thus the officer lacked probable cause or reasonable suspicion.
The court viewed the roadway, heard testimony, and analyzed RSA 265:45, concluding the statute unambiguously requires signals for turns, lane changes, or starting from parked positions—but not for continuing through a roadway that narrows or for the ‘‘merge’’-type movement at the narrowing point.
Because the statute was unambiguous, the officer’s mistaken belief that a signal was required was not objectively reasonable under Heien, so the stop was unlawful and the motion to suppress was granted.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether RSA 265:45 required a signal where two lanes gradually merge into one (the narrowing point)	Potter: statute unambiguously does not require a signal for merging/narrowing movements; no lane change or turn occurred	Government: statute ambiguous; movement could be read as a turn or lane change requiring a signal	Court: RSA 265:45 unambiguous—signals required for turns, lane changes, or starting from parked positions, not for the observed merge/narrowing movement; no signal required
Whether the officer’s mistake of law was objectively reasonable under Heien so as to validate the stop	Potter: officer’s interpretation was objectively unreasonable because statute is clear	Government: even if mistaken, reasonable judges could differ; under Heien the mistake was objectively reasonable	Court: applying Heien and the "reasonable judge" lens, the statute was not genuinely ambiguous and the officer’s mistake was not objectively reasonable; stop unconstitutional

Heien v. North Carolina, 574 U.S. 54 (2014) (an officer’s reasonable mistake of law can justify a seizure only if the mistake is objectively reasonable)
Whren v. United States, 517 U.S. 806 (1996) (traffic stops are Fourth Amendment seizures requiring probable cause or reasonable suspicion)
Brendlin v. California, 551 U.S. 249 (2007) (occupants of a stopped vehicle are seized during a traffic stop)
Rakas v. Illinois, 439 U.S. 128 (1978) (burden on suppression movant to show a Fourth Amendment violation)
United States v. Jimenez, 507 F.3d 13 (1st Cir. 2007) (ambiguity requires more than a plausible alternate construction)
United States v. Lawrence, [citation="675 F. App'x 1"] (1st Cir. 2017) (applies Heien and the “reasonable judge” framework to assess objective reasonableness)
Mahaffey v. State (Mahaffey I), 316 S.W.3d 633 (Tex. Crim. App. 2010) (construing a similarly worded signaling statute to hold a merge-like movement was not a signal-required turn)
United States v. Flores, 798 F.3d 645 (7th Cir. 2015) (officer’s mistaken statutory reading was not objectively reasonable where statute’s plain meaning contradicted the officer’s view)