If you're a Chicago landlord or tenant in an apartment covered by the CRLTO, you've got two levels of problems that can possibly arise. One type is your standard, run of the mill maintenance issue. For most of these, the landlord has 14 days from the time they are notified in writing of the problem to fix the issue before the tenant can invoke the law. Other problems are considered "essential services" and must be repaired within a much tighter timeframe: 72 hours.