What distance can a officer use deadly force on a person with a knife?

Answer 1

Once an officer can justify the need to use deadly force it doesn't matter what means he uses. It could be Baton, butter knife or running you over with a vehicle.

To justify deadly force the general standard is to protect himself or others from death or grievous bodily harm.

There are many rules on deadly force and they can vary on department or state. For instance using a Baton above the nipples can be considered deadly force by some Departments.

If you spray an officer with pepper spray he/she could be justified in using deadly force.

Most department I know use a 1 + 1 theory of control.

Using a scale of 1 to 10 with 1 being presence and 10 being Deadly force. An Officer is allowed to use at least one level above the level of force being exerted by a subject.

For instance if you pull away from an Officer he/she can use a control hold or empty hand control. If it escalates and you attempt to strike an officer with a closed fist he can spray you with a chemical aerosol and so on.

Of course each situation is different and it can go from 1 to 10 in a heartbeat.

Answer 2

It depends on where you are. In the U.S. many police departments have different policies, but very generally speaking legally, an officer can use deadly force against a person with a knife or other contact weapon when that person is within a distance where the officer is in danger, or another way to say it is, when the attacker is in useful range of whatever weapon he or she is using. People generally tend to think of knives and other contact weapons as only dangerous within a few feet, but a person can get close to you much faster than most people realize.