Contracts are not always static between the two original signatories -- rights and duties under them can move to new parties, but assignment and delegation move different things and follow different rules. An assignment transfers a right: the assignor's ability to receive a payment or other performance passes to the assignee, who can then enforce it directly against the party who owes it. A delegation transfers a duty: the delegating party arranges for someone else to actually perform the obligation, but, critically, delegation alone does not erase the delegator's own underlying liability if the delegate fails to perform.

Most real transactions combine both -- a party assigns its rights and delegates its remaining duties under the same contract to the same transferee -- but courts and the UCC treat them as analytically separate questions with separate limits. Confusing the two, or assuming that transferring one automatically discharges the transferring party from the other, is one of the more common and consequential mistakes in this area.

An assignment is a present transfer of a right the assignor already has under a contract -- most commonly the right to receive payment or delivery. Once validly assigned, the assignee steps into the assignor's shoes for that right and can sue the obligor directly if it is not honored; the assignor generally drops out of the picture for that specific right, though it can remain liable to the assignee under implied warranties of the assignment itself (that the right exists and has not already been assigned elsewhere).

A delegation is different in kind: it is an arrangement for someone else to perform the delegator's own duty. UCC 2-210 and Restatement (Second) of Contracts Section 318 govern the modern default rule -- delegation is generally permitted unless the contract forbids it or the obligee has a substantial interest in having the original party personally perform (a rule most forceful for personal-services and highly discretionary obligations). Unlike assignment, delegation alone does not discharge the delegator; the delegator remains liable if the delegate fails to perform, unless the obligee agrees to a novation releasing the original party.

Not every right is freely assignable, and not every duty is freely delegable. Rights are typically non-assignable when assignment would materially change the obligor's duty or materially increase its risk or burden, when the contract contains an enforceable anti-assignment clause (though many jurisdictions and the UCC construe such clauses narrowly, often as barring only the power to assign rather than voiding an assignment that happens anyway, unless the clause is explicit), or when assignment is barred by statute or by the fundamentally personal nature of the right, such as personal-injury claims in many jurisdictions.

Duties are typically non-delegable when the obligee has a substantial interest in the specific identity, skill, or judgment of the original party -- a portrait commissioned from a particular artist, or a contract turning on one party's unique reputation or discretion -- since forcing the obligee to accept a substitute performer would deprive it of something it specifically bargained for.

A party asserting rights as an assignee must show a valid, effective assignment -- present intent to transfer, adequate description of the right, and no bar to assignability -- and typically must show the obligor received notice, since an obligor who pays the original assignor without notice of the assignment is generally discharged despite the earlier assignment.

A party trying to hold an original obligor liable despite a delegation must show the delegation did not amount to a novation -- that the obligee never agreed to release the original party and substitute the delegate in its place. The party seeking to escape liability, by contrast, bears the burden of proving the obligee's clear assent to a full novation, which courts do not lightly infer from mere acceptance of the delegate's performance.

In Juricratic, assignment and delegation disputes are modeled as two separate but related claim paths from the same underlying contract, because a case can turn on the assignee's right to sue directly (the assignment path) while the original delegator remains simultaneously exposed on the duty side (the delegation path) unless a novation is separately proven -- treating the two as a single fused question misses real strategic distinctions on liability.

A user can sweep dials on whether the contract restricts assignment or delegation, whether the obligee received timely notice of an assignment, and whether the facts support a full novation releasing the original party, to observe how the modeled exposure shifts between the assignee, the delegator, and the delegate. These remain simulation inputs for war-gaming who bears liability, not a prediction of how a specific court will read the transfer.