The language the lawyers for Utah used is derived from a similar 2008 case Herring v. United States in which a clerical error, the warrant out for Herring in the system was a mistake, led to an unlawful arrest and uncovered evidence. The court's ruling in Herring set precedent that evidence obtained under police mistakes that were isolated negligence rather than a systematic error or disregard of constitutional rights do not violate a criminal defendant's Fourth Amendment rights. The court's ruling concluded the test of deterrence on the exclusionary rule was used as the Officers based on the information they had, made a ‘good' stop and the resulting evidence that was uncovered, though stemming from a isolated mistake wasn't a threat to the deterrent effect of the exclusionary rule. (2) A ruling in Utah v. Strieff could take precedent a step further in lessening the scope of Fourth Amendment protections.
The lawyers for Strieff as well as Justice Sotomayor and Justice Kagan argued that the extension of this argument would give too much latitude to law enforcement, especially in areas with high percentage of citizens with outstanding warrants. If the court sides with Utah, the lawfulness of the stop will not come into question when deciding the admissibility of the evidence; solely the lawfulness of the search will be considered.
With the recent death of Justice Antonin Scalia, the result of this case is up in the air. Recent attacks by conservatives on the scope of the 4th Amendment are in favor of more power and discretion of law enforcement. A 4v4 tie would hold up the ruling of the Utah Supreme Court, ruling that the evidence could not be used as the initial stop was not supported by reasonable individual suspicion.
A victory for Utah would be a devastating blow for the protections guaranteed by the Fourth Amendment and could substantially impact the relationship the Police have within communities. As highlighted by justice Sotomayor and Kagan during oral arguments the removal of the exclusionary rule in this case could incentivize police officers to make more unlawful stops; especially in neighborhoods where a high percentage of the residents have outstanding warrants. The removal of this deterrent could have a negative impact on the already strained relationship between law enforcement and the people in these communities.