Self-Defense is the right to defend yourself if you are attacked or feel in danger. Every state, including Illinois, has different laws that define what self-defense means. In Illinois, you can use reasonable force to defend:

• Yourself,
• Someone else,
• Your home, and
• Your personal property. 

The following conditions must exist to justify the use of force:

• There's an imminent danger or threat to you, someone else, or your property,
• The threat is unlawful,
• You believe that a danger exists that requires force, and
• You use force that is equal to the force of the threat.

You also cannot overreact or act unreasonably when defending yourself with force.

Illinois court have said that “imminent” means reasonably probable, not merely possible, and refers not to a future threat but to one that is present or immediate.

In most cases, you cannot claim self-defense if you are the aggressor. An aggressor is someone who:

• Is trying to commit, committing, or fleeing after a forcible felony,
• Intentionally provokes the use of force against themselves to then use that force as an excuse to physically harm another person, or
• Intentionally provokes others to use force against themselves.

However, an aggressor can use force only if:

• The use of force against them is so great that they reasonably believe they are about to be seriously injured or killed, and they tried to escape without using force, or 
• They stop physical contact and make it clear that they want to stop using physical force, but the other person keeps using force against them.

Note that only an aggressor has a duty to escape from the situation before using force in self-defense.

When using self-defense, there are 2 levels of force:

• Regular force: Force that stops someone's unwanted movements or actions, and 
• Deadly force: Force that causes or is intended to cause serious bodily harm or death.

Regular force

You can use regular force to defend:

• Yourself or someone else against an attack,
• Against an attack or unlawful entry into a home, and
• Against interference with other property in your possession.

However, you are not allowed to use force to resist an arrest by a police officer, even if the arrest is unlawful.

Deadly force

Defense of person

If you’re defending yourself or someone else, you can use deadly force if you reasonably believe it’s necessary to prevent:

• Imminent death or great bodily harm to yourself or another person, or
• A forcible felony, including sexual assault, battery, murder, robbery, and arson.

Defense of home

You can use deadly force to prevent an assault or threat of violence against yourself or someone else in a home or building if:

• You use it against someone who is trying to enter in a violent manner, or
• You reasonably believe that such force is necessary to prevent a forcible felony in the building.

Defense of personal property

Deadly force is generally not allowed when you are protecting your own personal property. You can use deadly force only if you reasonably believe that such force is necessary to prevent a forcible felony.