While I would like to agree... look at the exact wording of the law:
RCW 9A.52.070
Criminal trespass in the first degree.
(1) A person is guilty of criminal trespass in the first degree if he or she knowingly enters or remains unlawfully in a building.
(2) Criminal trespass in the first degree is a gross misdemeanor.
Notice the OR between "ënters" and "remains"
Could one argue that the signed policy document is already prior notice?
Sure. But prior notice doesn't necessarily enter into the equation. Prior notice is
presumed with respect to crimes ("ignorance of the law is no excuse"), but not presumed with respect to civil wrongs. You need to read a bit farther in your emphasized portion of the statute to understand, e.g., "(1) A person is guilty of criminal trespass in the first degree if he or she
knowingly enters or remains unlawfully in a building." The crucial word here is "unlawfully."
For example, a shopping mall may have a notice posted at its entrance that says that firearms are not allowed in the mall and that the mall considers entry a "crime" and, that by entering, you agree that it is a trespass. Even if you read the notice, is your entry a crime? Not necessarily. If you enter with a firearm, that entry, in and of itself, is not unlawful -- you have entered a place of business generally held open to the public (assuming you can lawfully possess a firearm), which is not an act that harms the state (such as entering a private residence or place of business not generally open to the public without consent). Before that entry can become a trespass, someone in authority must give you, personally, notice that you are trespassing and must leave. If you then do not leave, your remaining is the unlawful act of trespass. Similarly, if you have been trespassed on a prior occasion (i.e., been given express notice that you, personally, are trespassed from the mall), a subsequent entry would likely be considered by the state as a criminal trespass (unless that entry is permitted by conditions, such as not possessing a firearm on the premises, and those conditions are met).
While one is presumed to know what the law proscribes, one is not presumed to know the proscriptive policies of a business. If you have been personally notified that firearms are not permitted at your place of business, and you then enter with a firearm against that policy, even though your employer may be able to offer evidence that you committed the crime of trespass (which the
state must allege and then prove), your prior notice of the policy
cannot be construed as a
legal admission of guilt of the commission of a crime by violating that policy. The signing of an employee agreement is a civil contractual matter and agreement to its terms is only a contract between private entities. Any violation of those terms is a simple breach of contract, not a crime with respect to the
interests of the employer.
Private entities cannot contractually agree that a particular act constitutes a crime (well, of course they can
agree that it is, but that agreement doesn't mean anything, legally). Whether a particular act constitutes a crime is a
legal conclusion, which conclusion is reserved entirely to the state and must be proved.
But, you raise an interesting point.
As a matter of clarification, the "or" between "enter" and "remains" means that one is guilty of criminal trespass if (s)he 1) enters a building unlawfully (e.g., a private residence or place of business not generally open to the public, as discussed above), or 2) remains in a building unlawfully -- implying that the individual has been given explicit notice that the act of a particular remaining is unlawful. In other words, the entry may be lawful but the actor is notified that (s)he is now trespassing and must leave.