What tocomotose said is MOSTLY true... the difference is that you can use deadly force in your home, even if you see no direct physical threat.
The Utah Constitution (Article 1, Section 6) says:
The individual right of the people to keep and bear arms for security and defense of self, family, others, property, or the state, as well as for other lawful purposes shall not be infringed; but nothing herein shall prevent the Legislature from defining the lawful use of arms.
Utah law then breaks down deadly force into three categories - defense of person, defense of habitation, and defense of persons on real property.
Defense of person (Utah code 76-2-402)
This one is pretty straight forward. You can use deadly force to prevent death or serious bodily injury to yourself or a third person.
Of note, you do not have a duty to retreat from the force or threatened force. 'Forcible felony' includes almost all violent felonies, but NOT burglary of a vehicle unless you're in the vehicle at the time. In other words, if you shoot someone that is pulling out of the driveway in your car, you'll likely go to jail.
Defense of habitation (Utah code 76-2-405)
This defines that deadly
force can be used to protect your habitation
(note, this includes temporary habitations like camps and mobile homes) only when:
(a) the entry is made or attempted in a violent and tumultuous manner, surreptitiously, or by stealth, and he reasonably believes that the entry is attempted or made for the purpose of assaulting or offering personal violence to any person, dwelling, or being in the habitation and he reasonably believes that the force is necessary to prevent the assault or offer of personal violence; or
(b) he reasonably believes that the entry is made or attempted for the purpose of committing a felony in the habitation and that the force is necessary to prevent the commission of the felony.
It further clarifies that you are presumed to have acted reasonably if these conditions exist (in other words, you shouldn't be charged with anything).
Of note, you CAN use deadly force to protect your property WITHIN YOUR HABITATION even if you see no personal, physical threat.
In other words, if someone is in my home to steal my radio (a felony), I don't have to wait until that person aims his gun at me to use deadly force. It is presumed that if the person is not supposed to be there and is committing a felony, that the person is a personal threat.
Now, while you legally could shoot someone stealing your radio, making up your mind to just automatically shoot anyone in your home is likely setting you up for a disaster.
Deadly force in defense of persons on real property. (Utah code 76-2-407)
This defines that one can use deadly force in defense of persons (yourself or others) when you ARE NOT in your habitation, if:
* it is in your control (e.g., your place of employment, if under your charge)
* you are trying to stop or prevent trespass
* trespass is made violently (note that surreptitious or by stealthy entrance is not justification for force here as it is with your habitation), AND
* you believe the person will be violent against a person OR the person will commit a forcible felony that poses imminent peril of death or serious bodily injury to a person
Of note, all four conditions must all apply here. Notice that deadly force is only allowed to protect persons, NOT the property itself as it is for your home. In other words, if you're a manager of grocery store, you can't shoot a kid that sneaks in after hours and steals a Snickers bar.
Now, with other property that is yours or in your care (Utah code 76-2-406)
, you are NOT justified in using deadly
force unless any of the above conditions apply (though you can still use force - take it back, rough them up a bit, etc.). This means that if someone steals your wallet on the street, you can't shoot them just for this reason.