Legal Question in Business Law in Illinois

This is an interesting case of contractual interpretation, and it could go either way depending on the facts, the judge, and the law. Moreover, without seeing the exact language of the contract, it is difficult to advise you.

If either you or he are uncertain, you could file a "declaratory action" to determine your legal rights. In such an action, he would have defenses such as that (1) you hadn't "started" the demolition job because the trailer remained intact; (2) there was no valid contract because you did not agree on the parameters of what you could do with the trailer; and (3) you breached the contract by failing to demolish the trailer. You could make counter-arguments like the one here, that you acquired title to the trailer when you took it and he has no recourse.

He can also sue you for "unjust enrichment." You took a trailer for demolition purposes and were "unjustly enriched" by its value.

If I were you, I'd adopt a wait and see approach. How much was the trailer worth? What is left from the balance? If enough money is involved, bring suit. If not, wait for him to do so, but know that he has 5 years under the statute of limitations.