1. Because Liv did not attempt to direct her interest in the SIP benefits to the Estate or any other potential beneficiary, her waiver did not constitute an assignment or alienation rendered void under §1056(d)(1). Pp. 5–13.

        (a) Given the legal meaning of “assigned” and “alienated,” it is fair to say that Liv did not assign or alienate anything to William or to the Estate. The Fifth Circuit’s broad reading—that Liv’s waiver indirectly transferred her interest to the next possible beneficiary, here the Estate—is questionable. It would be odd to speak of an estate as the transferee of its own decedent’s property or of the decedent in his lifetime as his own transferee. It would also be strange under the Treasury Regulation that defines “assignment” and “alienation.” Moreover, it is difficult to see how certain waivers not barred by the antialienation provision e.g., a surviving spouse’s ability to waive a survivor’s annuity or lump-sum payment, see Boggs v. Boggs, 520 U. S. 833 ; 29 U. S. C. §§1055(a), (b)(1)(C), (c)(2), would be permissible under the Fifth Circuit’s reading. These doubts, and exceptions calling the Fifth Circuit’s reading into question, point the Court toward the law of trusts that “serves as ERISA’s backdrop.” Beck v. PACE Int’l Union, 551 U. S. 96 . Section 1056(d)(1) is much like a spendthrift trust provision barring assignment or alienation of a benefit, see Boggs, supra, at 852, and the cognate trust law is highly suggestive here. The general principle that a designated spendthrift beneficiary can disclaim his trust interest magnifies the improbability that a statute written with an eye on the old law would effectively force a beneficiary to take an interest willy-nilly. The Treasury reads its own regulation to mean that the antialienation provision is not violated by a beneficiary’s waiver “where the beneficiary does not attempt to direct her interest in pension benefits to another person.” Brief for United States as Amicus Curiae 18. Being neither “plainly erroneous [n]or inconsistent with the regulation,” the Treasury Department’s interpretation is controlling. Auer v. Robbins, 519 U. S. 452 . ERISA’s QDRO provisions shed no light on the validity of a waiver by a non-QDRO. Pp. 5–11.

        (b) DuPont’s additional reasons for saying that ERISA barred Liv’s waiver are unavailing. Pp. 11–13.

    2. Although Liv’s waiver was not nullified by §1056’s express terms, the plan administrator did its ERISA duty by paying the SIP benefits to Liv in conformity with the plan documents. ERISA provides no exception to the plan administrator’s duty to act in accordance with plan documents. Thus, the Estate’s claim stands or falls by “the terms of the plan,” 29 U. S. C. §1132(a)(1)(B), a straightforward rule that lets employers “ ‘establish a uniform administrative scheme, [with] a set of standard procedures to guide processing of claims and disbursement of benefits,’ ” Egelhoff v. Egelhoff, 532 U. S. 141 . By giving a plan participant a clear set of instructions for making his own instructions clear, ERISA forecloses any justification for enquiries into expressions of intent, in favor of the virtues of adhering to an uncomplicated rule. Less certain rules could force plan administrators to examine numerous external documents purporting to be waivers and draw them into litigation like this over those waivers’ meaning and enforceability. The guarantee of simplicity is not absolute, since a QDRO’s enforceability may require an administrator to look for beneficiaries outside plan documents notwithstanding §1104(a)(1)(D). But an administrator enforcing a QDRO must be said to enforce plan documents, not ignore them, and a QDRO enquiry is relatively discrete, given its specific and objective criteria. These are good and sufficient reasons for holding the line, just as the Court did in holding that ERISA preempted state laws that could blur the bright-line requirement to follow plan documents in distributing benefits. See Boggs, supra, at 850, and Egelhoff, supra, at 143. What goes for inconsistent state law goes for a federal common law of waiver that might obscure a plan administrator’s duty to act “in accordance with the documents and instruments.” See Mertens v. Hewitt Associates, 508 U. S. 248 . This case points out the wisdom of protecting the plan documents rule. Under the SIP, Liv was William’s designated beneficiary. The plan provided a way to disclaim an interest in the SIP account, which Liv did not purport to follow. The plan administrator therefore did exactly what §1104(a)(1)(D) required and paid Liv the benefits. Pp. 13–18.

497 F. 3d 426, affirmed.

    Souter, J., delivered the opinion for a unanimous Court.

 Case below: Kennedy v. Plan Administrator for Dupont Savings and Investment Plan (5th Cir 08/15/2007) 
Official docket sheet 
Certiorari granted: February 19, 2008. 
Oral argument: October 7, 2008.   

Certiorari Documents: 

• Petition for Writ of Certiorari 
• Brief of respondent Maine State Employees Association, SEIU Local 1989 in opposition 
• [Respondent Karass, State Controller, et al. filed a waiver of their right to respond to the petition.] 
• Reply of petitioner 

• For Petitioner: Stacy L. Kelly; 1925 Lexington; Houston, TX  77098; slkesq55@comcast.net; (713) 408-8134. 
• For Respondent: Mark I. Levy; Kilpatrick Stockton, LLP; 607 14th Street, NW, Suite 900; Washington, DC  20005; mlevy@kilpatrickstockton.com; (202) 824-1437.