This question came from one of our users:
"I have an issue where my flatmate has made things unbearable for me in my apartment. I moved out, and I have been trying to do a sublease for my room, but she is so hostile that people don’t want to stay there. She has been hostile towards me, too. I would like to know if I can break my lease."
Yes, if violence has occurred. Generally, in Illinois, a lease can usually be broken for a few reasons, including a hostile roommate, if the circumstances surrounding the breaking of a lease involve domestic violence, stalking, or sexual assault. Suppose you are a victim of violence or abuse by a co-tenant. In that case, you may be able to terminate your lease early, with no penalty, if you provide your Landlord with evidence of abuse or violence and give notice of your intent to break the lease. However, if hostility between you and your roommate is not related to abuse or violence, breaking the lease will generally require an agreement with your Landlord confirming you can break the lease, sublet the residence, or pay penalties for breaking the lease early.
Let's Break it Down
Of course, if you are in the middle of a serious argument/disagreement with your roommate, and the environment no longer feels safe, either you or your roommate may want to move out or have the co-tenant move-out. It is important to note that, though you may want to, you cannot "evict" a co-tenant or change the locks on a co-tenant because the eviction process is a remedy reserved solely for landlords. Certainly, it may be more efficient for roommates to potentially prevent serious conflicts/arguments from arising in the first place by tackling major issues as they arise. What happens if things go nuclear and you want to leave, but you have time left on your lease?
What Are Your Options
Non-Violent Hostility:
If your roommate's behavior is simply annoying or disruptive but not violent, you will likely need to negotiate with the Landlord or face penalties for breaking the lease early.
Finding a New Roommate:
With the Landlord's approval, you may also be able to search for a new tenant to sublet for you or for your roommate. They would then be able to take over the lease. This option may be provided for in your lease. Otherwise, you may have to negotiate with the Landlord and describe the situation and your reason for subleasing.
Small Claims Court:
On another point, if your roommate ends up causing you financial harm (e.g., not paying rent, destroying the property), you may be able to bring a suit against them in small claims court for the damage they caused that you had to cover.
Violent Hostility:
Suppose your roommate's behavior goes beyond argumentative, annoying, or disruptive and crosses the threshold into viable threats, abuse, or violence. In that case, you may likely be able to terminate your lease early on proof of violence submitted to your Landlord.
Furthermore, in cases of domestic violence, your Landlord may be able to evict the perpetrating co-tenant and change the locks, even if you, as the victim, want to stay at the rental property.
Bottom Line: Illinois state law provides early termination rights for tenants who are victims of domestic or sexual violence (or who face an imminent threat of such violence at the premises), provided that specified conditions are met (such as the tenant providing evidence, such as a police report). (765 Ill. Comp. Stat. § 750/15.)
Essentially, you may be able to terminate your lease early without paying the rest of the rent. Alternatively, the Landlord may be able to evict the offender and change the locks. Note that landlords are typically not allowed to discriminate against tenants or prospective tenants who have restraining orders against them, such as by refusing to rent to them.

Landlord's Duty: Safety Issues
In extreme situations that result in violence, please do not delay calling the police, especially if your roommate is threatening your physical safety or otherwise committing violence in violation of the law. If violence has occurred against you, your Landlord may likely start eviction proceedings against the offending roommate,
They would like to initiate an eviction to avoid liability in the event your roommate does end up harming you.
Landlord's Duty to Find a New Tenant in Illinois
If you don't have a legal justification to break your lease (as in the situations described above), you may still be off the hook for paying all the rent due for the remaining lease term. Landlords must mitigate (attempt to lessen or keep monetary losses to a minimum) their damages. Under Illinois law, your Landlord must make reasonable efforts to re-rent your unit instead of charging you for the total remaining rent due under the lease. This must be so regardless of your reason for leaving. (735 Ill. Comp. Stat. § 5/9-213.1.) In some cases, you may not have to pay much, if any, additional rent if you break your lease. For example, you must move before your lease is up to take a new job, and the Landlord rented your previous unit the month after you left. You need to pay only the amount of rent the Landlord lost because you moved out early (a month's rent).
Generally, if you break your lease and move out early without legal justification, your Landlord can't, and usually won't, just sit back and wait until the end of the lease and sue you for the amount of lost rent due under the lease. Your Landlord must try to rent out the unit fairly quickly. They will subtract the rent received from any new tenants from the total amount of rent owed by you.
It is important to note that the Landlord doesn't need to accept just any Tom or Harry. The Landlord is not obligated to relax their standards to rent to unacceptable tenants. For example, to accept someone with a poor credit history or a history of defaulting on rent. Similarly, the Landlord is not required to rent the unit for less than what is fair in the market or to disregard everything else (like repairs to other units) to immediately attempt to rent out the abandoned unit. Critically, the Landlord can also add legitimate expenses to your bill. For example, to rent the apartment, the Landlord runs an ad on an online forum. The costs of advertising the property could be added to the amount you owe for breaking the lease early.
This means, of course, that if your Landlord tries to rent out your unit again and can't find an acceptable tenant, you are going to have to pay the amount of rent due on the remainder of your lease term. Your Landlord will probably use your security deposit to cover the amount you owe, but if your deposit is not enough, you are likely going to face a suit for non-payment of rent due and/or the lease violation. There are limits to the amount that can be collected in small claims court. Check your local jurisdiction.
Minimizing Your Financial Responsibility if Breaking a Lease
If you don't have legal justification but want to leave your rental unit early, there are more effective options than just leaving and hoping your Landlord gets a new tenant post haste. You can limit the amount of money you need to pay your Landlord in many ways, which will help ensure a good reference as you look for your next place to rent.
Provide as much notice as possible and in writing. A sincere letter explaining why you need to leave early can often do a lot of good to come to an agreement with more reasonable landlords. Offering an excellent sublessor is also a viable option to convince your Landlord that breaking your lease early will not cause them undue hardship.
Designed for general information use only. The content above does not constitute legal advice or the formation of an attorney/client relationship.