Unless they have a warrant or there are exigent circumstances, you do not have to let them in. You do not even have to answer the door. If they say they have a warrant ask them to hold it up to the door or to slip it under the door. The police may break down the door if exigent circumstances exist such as danger of fleeing, hiding someone or some other emergency that would make the getting of a warrant impractical. If they leave a card, immediately call us. A lawyer can speak to the police to find out what it is that they want.