Crime lab data from the Washington State Patrol Forensic Laboratory Services Bureau: The WSP operates the official crime labs for the state of Washington. The FLSB analyzes all evidence for drug-related crimes in the state, except for toxicology (drug presence in humans). This evidence might include pills in bottles, bags with powder or botanical materials, pipes with residue, and so on. A "drug case" refers to a unique FLSB case number with at least one result positive for that drug (any drug or class of drug of interest). Drug mixtures, such as counterfeit pills combining two or more drugs, and seizures of multiple kinds of drugs in one container mean that counts of cases across drug types exceed the total number of cases with any drug confirmed.
Crime lab cases reflect a combination of who gets arrested, which cases get prosecuted, which items get sent to a lab for testing, and whether the items have sufficient quantity to be tested. Rates and trends may thus be influenced by policy and practice factors such as attention to distribution and diversion of non-violent arrestees. A 2008 US Supreme Court case also may have affected police evidence gathering procedures. More recently, the February 2021 decision by the state Supreme Court in State v. Blake effectively decriminalized many simple possession cases.
Only crime lab submissions from an agency clearly operating within a single county are associated with a county. Those originating from multi- or cross-county agencies, such as cross-jurisdiction crime task forces, some Washington State Patrol detachments, statewide (e.g., the Department of Fish & Wildlife) or federal agencies (e.g., Homeland Security), or federal law enforcement, are included in the statewide rate, as are other entities such as Olympic National Park and railroad companies that span multiple counties. Benton and Franklin Counties are prime examples of this, where many seizures might be conducted by the Tri-Cities Metro Drug Task Force and thus not assigned to either Benton or Franklin, creating an undercount. Changes in county rates may therefore reflect changes in the share of seizures by such agencies.
The exceptions to this county-spanning consideration are Native American reservations, some of which have small portions in other counties. The most obvious example is the Colville Reservation, which covers a large portion of Okanogan County and a smaller but substantial share of Ferry County, while the Confederated Tribes of the Colville Reservation also have small land holdings in Chelan County. We believe that most of the reservation's approximately 8000 residents live in Okanogan County, and assign submissions from the Colville Tribal Police to that county. Results for Ferry County may thus be undercounted.