WSU study: officers rely on 'survival Spanish' and passengers when language barriers arise in traffic stops

A Washington State University researcher presented a randomized study of body-worn camera footage that analyzed 84 traffic stops involving Pasco Police Department officers; 43 of those stops involved language barriers. Dr. Hillary Mellinger, an assistant professor who conducted the work with the university’s Complex Social Interactions lab, summarized methods and practical findings and recommended a mix of hiring, training and technology improvements.

"We coded until basically I found I wasn't reaching any new findings, which happened at 84 police stops, of which 43 involved language barriers," Dr. Mellinger said. The study found officers most commonly used "survival Spanish" (79% of stops) — limited law-enforcement vocabulary aimed at communicating key points — pantomime (63% in stops with barriers), adult passengers or civilians as ad hoc interpreters (21%), bilingual officers (12%), and Google Translate (7%). In the random sample, researchers observed no use of the formal language line, a finding researchers attributed to traffic noise and time constraints.

Researchers highlighted a core positive: officers stated the reason for the stop in 96% of cases, even when language barriers existed. Dr. Mellinger recommended agencies increase Spanish-language capacity, invest in appropriate technology for traffic-stop conditions, and prioritize training on how and when to switch resources (e.g., call a bilingual officer for criminal matters rather than rely on passengers).

Council members asked about the role of AI and off-the-shelf tools; Dr. Mellinger said AI and vendor tools show promise but require careful validation for traffic-stop use, where volume, connectivity and noise can reduce reliability. Police leadership described the study as evidence of existing training and a tool to improve bilingual capacity and outreach.