Hi phorsfall my understanding is that WA state law defines the term 'spring blade knife' as follows (excerpt taken from 2012 legislation):
9 "Spring blade knife" means any knife, including a prototype,
10 model, or other sample, with a blade that is automatically released by
11 a spring mechanism or other mechanical device, or any knife having a
12 blade which opens, or falls, or is ejected into position by the force
13 of gravity, or by an outward, downward, or centrifugal thrust or
14 movement. A knife that contains a spring, detent, or other mechanism
15 designed to create a bias toward closure of the blade and that requires
16 physical exertion applied to the blade by hand, wrist, or arm to
17 overcome the bias toward closure to assist in opening the knife is not
18 a spring blade knife.
Reference:
http://apps.leg.wa.gov/documents/billdocs/2011-12/Pdf/Bills/House%20Passed%20Legislature/2347-S.PL.pdfI belive this would include all automatic knives, whether OTF or other design. These are generally prohibited in WA state with the exception of several categories of personnel. I believe this is limited to military, law enforcements, and fire/rescue personnel though the exact verbage of the exceptions is included in the link above.