Trespassing Law in Oregon:
There are both criminal and civil TRESPASS laws. Criminal trespass law is enforced by police, sheriffs, or park rangers. Civil trespass requires that the landowner initiate a private enforcement action in court to collect any damages for which the trespasser may be responsible, regardless of whether a crime has been committed. Traditionally, for either type of trespass, some level of intent is required. Thus, the trespasser must not simply unwittingly traverse another's land but must knowingly go onto the property without permission. Knowledge may be inferred when the owner tells the trespasser not to go on the land, when the land is fenced, or when a "no trespassing" sign in posted. A trespasser would probably not be prosecuted if the land was open, the trespasser's conduct did not substantially interfere with the owner's use of the property, and the trespasser left immediately on request.
TRESPASSING LAW IN OREGON: No person shall hunt upon the cultivated or enclosed land of another without first obtaining permission from the owner or lawful occupant thereof, or the agent of such owner or occupant. The boundaries of enclosed land may be indicated by wire, ditch, hedge, fence, water or by any visible or distinctive lines that indicate a separation from the surrounding or contiguous territory.
If you do not have written permission on you to hunt private land and are stopped by a game officer or police officer . They can prosecute you for criminal trespassing without the owners of the land even being involved.....