Basically, the cops can come into your house for a number of different reasons. The basic example is that they feel laws are being broken inside the house or someone is in danger. Example, they get called out for loud music, while they're at the door they hear a woman scream from inside the house. They now have the right to enter because they have evidence, the scream, that something unlawful, or a dangerous situation, is happening inside the house. They now have the right to enter. As for the searching safes that are in the house. Technically, they would need a warrant to search them. But, if you don't open it they'll just confiscate it until they go and get a warrant. Also, the cops are very sneaky. My uncle, who's a retired cop, has told me they use to do the following ALL the time and it stands up in court. They come to your house and knock on the door. You answer the door and you're talking to them through your screen door. They ask you to open the screen door so that they can see you better or talk to your better. The minute you do that you've just opened your house to them. Opening the screen door can be interpeted as inviting them into your house. And the minute you open the screen door they'll immediately step into your house and then it's over. I know it's TOTAL BULLSHIT!!! But, he told me it's done ALL the time and it stands up in court.