1. Non-consensual police stops of open carriers for simply open carrying is per se unlawful.
As you should already know, it is not unlawful to openly carry handguns in Washington, and that like most states, no license is required to open carry on foot, and local ordinances to the contrary are unlawful as a matter of state preemption law. RCW 9.41.290. The United States Supreme Court has established that it is a violation of the Fourth Amendment for the police to seize a person absent reasonable articulable suspicion ("RAS") of crime afoot. Terry v. Ohio, 392 U.S. 1 (1968). Accordingly, the Washington Court of Appeals has recently affirmed a trial court's holding that Washington law "does not and, under the Constitution, cannot prohibit the mere [open] carrying of a firearm in public." State v. Casad, 139 Wash.App. 1032 (Wash. App.Div.2 2007) (suppressing evidence of unlawful possession of firearms because stop of Defendant was not grounded in reasonable articulable suspicion of any crime).
Further, even during a valid Terry stop, the United States Supreme Court forbids police to even conduct a light pat down or seize weapons unless the subsequent to RAS for the stop, the "an officer is justified in believing that the individual whose suspicious behavior he is investigating at close range is [both] armed and presently dangerous to the officer or to others." 392 U.S. at 24. Stated another way, only "o long as the officer is [both] entitled to make a forcible stop, and has reason to believe that the suspect is armed **and dangerous** . . .may [he] conduct a weapons search limited in scope to this protective purpose." Adams v. Williams, 407 U.S. 143, 146 (1972) (emphasis added). So even if there were there to come a time that a Washington law enforcement officer properly seizes a person pursuant to RAS for brief investigatory purposes, the officer is not entitled to seize an openly carry weapon absent "reason to believe that the suspect is . . . [also presently] dangerous." Id. Should an open carrier stopped validly under Terry consensually produce a Concealed Pistol License, this fact weighs heavily against any officer's claim that the suspect is "presently dangerous" such that the gun maybe lawfully seized and serial numbers obtained. Accordingly, suppression of any evidence obtained in seizing the gun is likely under these circumstances.
2. Nonconsensual stops of open carriers to demand identification or check gun serial numbers is unlawful in Washington.
A mere report of a man with a gun is not grounds for a Terry stop. Florida v. J. L., 529 U.S. 266 (2000). Americans cannot be required to carry and produce identification credentials on demand to the police. Kolender v. Lawson, 461 U.S. 352 (1983). Washington does not have a "stop and ID" statute. However, even where a state enacts a "stop and ID" statute, stop must be limited to situations where RAS exists of a crime, and further, stop subject's statement of his name satisfies the ID requirement as Kolender, discussed supra, has not been overruled. Hiibel v. Sixth Judicial District Court of Nevada, 542 U.S. 177 (2004). Even where a state has established a duty to carry a license for some activity, absent RAS for the stop, the license cannot be demanded. State v. Peters, 2008 WL 2185754 (Wis. App. I Dist. 2008) (driver of vehicle has no duty to produce driver's license absent RAS) (citing Hiibel). Law enforcement officers seizing persons for refusal to show identification are "not entitled to dismissal of . . . [42 USC 1983 claims] based on qualified immunity." Stufflebeam v. Harris, 521 F.3d 884, 889 (8th Cir. 2008).