I think what you are looking for is called "common sense".

You won't be going around murdering people since it is common sense and you are brought up this way.

Murder and dirty joke is not the same thing if you have any common sense and that's why usually murder has priority over dirty jokes in court. You usually don't get sued for dirty joke. That's why we don't call dirty jokes a murder nor we call murder a joke.

And the common sense is what should set our priorities. Who would you rather see in court first mass murderer or a thief? And on what grounds do you decide this? How do YOU decide which is more offensive? Do we have scales for it?