1. Section 3-203 is based on former section 3-201 which stated that a transferee received such rights as the transferor had. The former section was confusing because some rights of the transferor are not vested in the transferee unless the transfer is a negotiation. For example, a transferee that did not become the holder could not negotiate the instrument, a right that the transferor had. Former section 3-201 did not define "transfer". Subsection (a) defines transfer by limiting it to cases in which possession of the instrument is delivered for the purpose of giving to the person receiving delivery the right to enforce the instrument.
Although transfer of an instrument might mean in a particular case that title to the instrument passes to the transferee, that result does not follow in all cases. The right to enforce an instrument and ownership of the instrument are two different concepts. A thief who steals a check payable to bearer becomes the holder of the check and a person entitled to enforce it, but does not become the owner of the check. If the thief transfers the check to a purchaser the transferee obtains the right to enforce the check. If the purchaser is not a holder in due course, the owner's claim to the check may be asserted against the purchaser. Ownership rights in instruments may be determined by principles of the law of property, independent of article 3, which do not depend upon whether the instrument was transferred under section 3-203. Moreover, a person who has an ownership right in an instrument might not be a person entitled to enforce the instrument. For example, suppose X is the owner and holder of an instrument payable to X. X sells the instrument to Y but is unable to deliver immediate possession to Y. Instead, X signs a document conveying all of X's right, title, and interest in the instrument to Y. Although the document may be effective to give Y a claim to ownership of the instrument, Y is not a person entitled to enforce the instrument until Y obtains possession of the instrument. No transfer of the instrument occurs under section 3-203(a) until it is delivered to Y.
An instrument is a reified right to payment. The right is represented by the instrument itself. The right to payment is transferred by delivery of possession of the instrument "by a person other than its issuer for the purpose of giving to the person receiving delivery the right to enforce the instrument". The quoted phrase excludes issue of an instrument, defined in section 3-105, and cases in which a delivery of possession is for some purpose other than transfer of the right to enforce. For example, if a check is presented for payment by delivering the check to the drawee, no transfer of the check to the drawee occurs because there is no intent to give the drawee the right to enforce the check.
2. Subsection (b) states that transfer vests in the transferee any right of the transferor to enforce the instrument "including any right as a holder in due course". If the transferee is not a holder because the transferor did not indorse, the transferee is nevertheless a person entitled to enforce the instrument under section 3-301 if the transferor was a holder at the time of transfer. Although the transferee is not a holder, under subsection (b) the transferee obtained the rights of the transferor as holder. Because the transferee's rights are derivative of the transferor's rights, those rights must be proved. Because the transferee is not a holder, there is no presumption under section 3-308 that the transferee, by producing the instrument, is entitled to payment. The instrument, by its terms, is not payable to the transferee and the transferee must account for possession of the unindorsed instrument by proving the transaction through which the transferee acquired it. Proof of a transfer to the transferee by a holder is proof that the transferee has acquired the rights of a holder. At that point the transferee is entitled to the presumption under section 3-308.
Under subsection (b) a holder in due course that transfers an instrument transfers those rights as a holder in due course to the purchaser. The policy is to assure the holder in due course a free market for the instrument. There is one exception to this rule stated in the concluding clause of subsection (b). A person who is party to fraud or illegality affecting the instrument is not permitted to wash the instrument clean by passing it into the hands of a holder in due course and then repurchasing it.
3. Subsection (c) applies only to a transfer for value. It applies only if the instrument is payable to order or specially indorsed to the transferor. The transferee acquires, in the absence of a contrary agreement, the specifically enforceable right to the indorsement of the transferor. Unless otherwise agreed, it is a right to the general indorsement of the transferor with full liability as indorser, rather than to an indorsement without recourse. The question may arise if the transferee has paid in advance and the indorsement is omitted fraudulently or through oversight. A transferor who is willing to indorse only without recourse or unwilling to indorse at all should make those intentions clear before transfer. The agreement of the transferee to take less than an unqualified indorsement need not be an express one, and the understanding may be implied from conduct, from past practice, or from the circumstances of the transaction. Subsection (c) provides that there is no negotiation of the instrument until the indorsement by the transferor is made. Until that time the transferee does not become a holder, and if earlier notice of a defense or claim is received, the transferee does not qualify as a holder in due course under section 3-302.
4. The operation of section 3-203 is illustrated by the following cases. In each case Payee, by fraud, induced Maker to issue a note to Payee. The fraud is a defense to the obligation of Maker to pay the note under section 3-305(a)(2).
Case #1. Payee negotiated the note to X who took as a holder in due course. After the instrument became overdue X negotiated the note to Y who had notice of the fraud. Y succeeds to X's rights as a holder in due course and takes free of Maker's defense of fraud.
Case #2. Payee negotiated the note to X who took as a holder in due course. Payee then repurchased the note from X. Payee does not succeed to X's rights as a holder in due course and is subject to Maker's defense of fraud.
Case #3. Payee negotiated the note to X who took as a holder in due course. X sold the note to Purchaser who received possession. The note, however, was indorsed to X and X failed to indorse it. Purchaser is a person entitled to enforce the instrument under section 3-301 and succeeds to the rights of X as holder in due course. Purchaser is not a holder, however, and under section 3-308 Purchaser will have to prove the transaction with X under which the rights of X as holder in due course were acquired.
Case #4. Payee sold the note to Purchaser who took for value, in good faith, and without notice of the defense of Maker. Purchaser received possession of the note but Payee neglected to indorse it. Purchaser became a person entitled to enforce the instrument but did not become the holder because of the missing indorsement. If Purchaser received notice of the defense of Maker before obtaining the indorsement of Payee, Purchaser cannot become a holder in due course because at the time notice was received the note had not been negotiated to Purchaser. If indorsement by Payee was made after Purchaser received notice, Purchaser had notice of the defense when it became the holder.
5. Subsection (d) restates former section 3-202(3). The cause of action on an instrument cannot be split. Any indorsement which purports to convey to any party less than the entire amount of the instrument is not effective for negotiation. This is true of either "Pay A one-half", or "Pay A two-thirds and B one-third". Neither A nor B becomes a holder. On the other hand an indorsement reading merely "Pay A and B" is effective, since it transfers the entire cause of action to A and B as tenants in common. An indorsement purporting to convey less than the entire instrument does, however, operate as a partial assignment of the cause of action. Subsection (d) makes no attempt to state the legal effect of such an assignment, which is left to other law. A partial assignee of an instrument has rights only to the extent the applicable law gives rights, either at law or in equity, to a partial assignee.