The short answer
Illinois courts interpret contracts to give effect to the parties’ intent, starting with the plain language of the document itself. Outside evidence, such as negotiations, usually comes in only if the language is ambiguous.
Why it matters
Most contract disputes are really interpretation disputes. How a court reads one sentence can decide the whole case, so understanding the rules shapes both your position and your settlement value.
Where it fits in your case
Whenever the parties read a provision differently, from a price clause to a termination right.
What to expect
Plain language first. Courts read the words in their ordinary meaning and in the context of the whole contract.
Ambiguity. A term is ambiguous only if it is reasonably open to more than one meaning. Disagreeing about it is not enough.
Specific over general. A specific provision usually controls over a general one on the same subject.
Integration clauses. A clause stating that the document is the entire agreement can limit reliance on earlier promises.
Against the drafter. Unresolved ambiguity may be construed against the party that drafted it, usually as a last resort.
What to do now
Read the disputed language alongside the rest of the contract.
Gather drafts, emails, and course of dealing in case the language is found ambiguous.
Look for definitions, order of precedence, and integration clauses.
Avoid conduct inconsistent with your reading while the dispute is pending.
What we need from you
The full contract with all exhibits and amendments, drafts and negotiation emails, and records of how the parties performed.
Common misconceptions
“What we discussed controls over what we signed.” Usually the written contract controls.
“Any disagreement makes the contract ambiguous.” A court decides whether language is ambiguous.