A lot of those laws vary by state, but more importantly, by the lease contract itself. Chances are, she's responsible for early termination fees, would probably lose her security deposit (goes towards the term fee) and would be hassled by the apt community or its collectors until she paid the balance off.
Here in South Carolina, the standard termination fee is 3 times the amount of monthly rent and you're required to give at least a 30-day notice to vacate.
An option she should explore, however, is if her current apt community has any locations in Illinois (assuming she's not living with you). I worked for a year and a half as an assistant property manager for a very large company that had apartment communities in 15 states. If she stays within the same company, they should let her just pay a small transfer fee and then the termination fee isn't an issue.
Usually, at least in South Carolina anyways, civil court judges will ALWAYS agree with apt communities once an individual has signed the lease agreement. She can try and fight it, but it will probably be unsuccessful.
The few times we waived termination fees at the community I worked at was when residents came in and honestly told us what was going on. Not coming in all fired up, trying to beat the contract.... but coming in humble, aware that they signed a legally binding contract, and wanting to see if other arrangements could be made before their account was sent to creditors.
Hope that helps!