Assignment transfers a contractual right. Delegation transfers performance of a duty. Most contracts are assignable and most duties delegable unless the agreement says otherwise or the duty is personal.
The delegating party remains liable. Delegation does not release the original obligor; only a novation, which requires the other party’s consent, does that. Businesses routinely believe they have escaped an obligation by assigning the contract when they have not.
Anti-assignment clauses are enforceable, but their wording controls. A clause prohibiting assignment of rights may not bar delegation, and one drafted as a covenant gives a damages claim while one drafted as a condition makes the purported assignment void. If the intent is to make an unconsented assignment ineffective, the clause must say so.
Change of control. A share sale is not an assignment of the target’s contracts — the counterparty is the same legal entity. Parties who care must add an express change-of-control trigger. Mergers vary by structure and by state law, and the analysis in an asset deal is different again.
Consent not to be unreasonably withheld is the common negotiated middle, and is worth adding a deemed-consent period so that silence does not block a closing.
Notice to the obligor matters on assignment of receivables: until notified, payment to the assignor discharges the obligation.