As a general rule, you do get to expect to have a certain level of privacy in your own home. This extends to the things that you own. The police cannot simply come in to your house and take items or perform a search without your permission, because that is your private property. Simply being members of the police department doesn’t give them the right to override that.
Likewise, if you throw something away inside of your home, you still have that expectation of privacy. That item is still your personal property, whether it’s in the trash or anywhere else. Items that are still on your property cannot be seized as evidence unless the police have a warrant or some other reason to legally enter that property.
When the item leaves your property
The problem becomes that the item may leave your property in your trash bin when you roll it out to the side of the road or set it by the curb. At that point, it is sitting on a public road and you have no more expectation of privacy. If the police wanted to, they could come by and look through your trash or simply take all of the contents with them.
People will sometimes argue that this was still their private property and they were trying to throw it away. But the location of the items makes a big difference in whether or not you still retain those property rights and the subsequent rights to privacy. Items that are in plain view in public – which includes your trash – do not get the same protections.
If you’re facing legal charges, be sure you know about all the defense options at your disposal. This is especially true if you believe the police violated your rights.