My question involves police conduct in the State of: washington

i was just curious about if i have a fence up in my driveway are the police still aloud to enter? i also asked them to leave my property and they did not do so and walked around to the back of my house to check things out because they suspected me of having a party. i was not having a party with any drinking it was just a few of my friends hanging out in my back yard. also there were no signs that would have implied i was having an alcoholic underage party.

were they aloud to do this. i thought that if there was a gate they were not aloud to enter. do i need to put up a no trespassing sign with contact information on it?