Someone recently asked about "dumpster diving" in Washington.  Dumpster diving comes up in three contexts:  (1) identity theft, (2) trade secrets, and (3) dumpster diving by the police.  Some states, such as Connecticut expressly address dumpster diving in their trade secrets statute [link].  In most other states this is left to default rules governing property and trespass.

There’s no statute aimed at “dumpster diving” in Washington. Nor do any cases (to my knowledge) expressly address this issue in the trade secrets context.  The key question will be whether the trash can is in an accessible area or whether the dumpster diver needs to encroach on private/bounded property in order to dive. Another issue will be whether the owner of the premises granted some sort of an “implied license” with respect to the area around the trash. (Some people have argued that if asked the owner would have granted permission, and therefore it is not a real trespass to look through someone’s trash can. This comes up particularly in urban areas.)

The issue of privacy in garbage also comes up in the context of police searches of garbage. There is one case in Washington which provides that people have reasonable expectation of privacy in their garbage, and a police search of the garbage violates this privacy.  The Washington case in question (which suppressed evidence obtained through a police search of the defendant's garbage) cited to a Seattle city ordinance which restricted access to trash cans. State v. Boland, 115 Wn.2d 571, 576 (Wash. 1990) (“Moreover, a Seattle ordinance makes it unlawful for anyone other than the owner of the trash can, or one authorized by the owner to place objects in the can, to remove its contents "except for collection.").  My quick search of the existing city ordinances did not uncover this ordinance (Seattle Municipal Code 21.36.100). (I think at some point the city transitioned to City-owned cans and changed the code.)

Because the license issue can muddle the trespass determination (and people can always argue that regardless of restrictions, the property owner in practice tolerated people looking through the trash) I would not rely on default property or municipal code regulations in determining that your trash cans are secure.  If someone is concerned about dumpster diving they should take security measures: (1) shred all sensitive documents and (2) keep trash cans locked and in a non-publicly accessible area so someone would have to clearly encroach/trespass to access. Posting signs may help as well.