Is it illegal to not answer your front door if a police officer knocks?

So if there's a police officer at your door, is it illegal to not open the door? No, it's not illegal. If they're knocking on your door and they don't have a warrant, you're not required to open the door. You're also not required to answer any questions. You can just stay silent, speak through the door, ask, do you have a warrant? Now, if they say they do have a warrant, there are two kinds of warrants that are possible. They can have an arrest warrant so they can enter your home if they reasonably believe that you're inside and they have an arrest warrant. Or if they have a search warrant, they can enter and search the areas that are listed inside of the warrant. So those two circumstances are required. You can ask them to slide the warrant under the door or give it to you through the window just so you can look at it, but you can't object to a warrant. But absent a warrant, you absolutely do not have to talk to police or open your door. There's also situations called exigent circumstances where police can enter your home without a warrant. If they believe that somebody's in danger, there's evidence that is being destroyed imminently, or if there's a fleeing suspect that's inside, they chase someone into the house, then they can enter without a warrant. So hopefully that answers your question.