There's no universal 'common law'. Each jurisdiction has its own, diverged "branch" of common-law, each with its own peculiarities. Primarily, based upon its

There's no universal 'common law'. Each jurisdiction has its own, diverged "branch" of common-law, each with its own peculiarities. Primarily, based upon its history. And as the legislative branch passes laws, they effect the power of, modify the scope of, or render inert many such judicial decisions. This is why I said "many common law jurisdictions', not just 'common law'. One vital part of common law, is intent. A door with a lock on it? And you pick it / disable it? It is going to be exceptionally difficult to prove benign intent here. An unlocked door? Well... Are your friends 'breaking and entering' by opening the door and walking in? Again, intent here... Did you knock, and "thought you heard something"? Again, intent. There have been many court cases, but as an example, for a while, in Ontario, Canada, it was common for police to knock at the door, and simply enter saying "Oh, I knocked.. but no one heard me." I kid you not. But let's take a step back here, and give you an example as to why this becomes more difficult with an unlocked door. Part of the issue here is, many houses have a covered, 'cold room' prior to the house proper. Yet, this is still part of the house. It has a roof and walls, a door. It is simply part of the house. In many colder climates, you enter this area. This is fully expected. You're now sheltered, but it isn't heated. When the owner opens the "door proper", blowing snow and wind won't enter their house. Ergo, to knock, you must approach the "real door" of the house, inside this room, and knock. It is also not immediately clear if the "very outside door" you are accessing, is a cold room, or the actual door of the house. How do you discover one way or the other? Why you open the door, and enter! Intent is primary here. Entry into an unlocked house does not prove intent, as there is no 'forced entry'. One thing ; in Canada, the police lay charges. A person need not even make a complaint, for the police to act. Nor does a person insisting that the police not charge someone, indicate this will happen! An example here ; the police discover assault of some form. They only need evidence, not willingness to 'charge'. Now take this legal position, and assign it to people entering houses. Your friend enters your house, as he always does, without even knocking. According to you, that's 'break and enter', yes? What differentiates here? Why, intent of course! Intent is primary, and a locked door creates a very strong validation of intent. An unlocked? Zero validation.