Let me clarify one point first. Individual retirement arrangements that are not part of ERISA plans are subject to state beneficiary designation rules. The IRS did not hold that the state lacked authority to reform a beneficiary designation in PLR 201628005. In fact, on page 5 the IRS stated, “In addition, although the Court order changed the beneficiary of IRA X under State law, the order cannot create a “designated beneficiary” for purposes of section 401(a)(9).” The IRS held that this change, however, was not effective int the determination of whether the designee was the decedent’s estate at the time of his death for purposes of determining the required Section 401(a)(9) minimum distributions.
RTK is correct that the plan terms determine the beneficiary of an ERISA plan, which I presume is the case with the 401(k) plan at issue. The Supreme Court has consistently held that ERISA preempts any state law that is contrary to the terms of an ERISA plan. See Boggs v. Boggs, 520 U.S. 833 (1997); Egelhoff v. Egelhoff, 532 U.S. 141 (2001), and Kennedy v. Plan Adm’r of DuPont Sav.& Inv. Plan, 555 U.S. 285 (2009 See generally Albert Feuer, When Do State Laws Determine ERISA Plan Benefit Rights?, 47 J. MARSHALL L. REV. 145, 282-292 (Fall 2013), abstract and full article available at http://ssrn.com/abstract=2440008.
The practical question is what does one do when one represents a plan that is confronted with a state-law order with respect to a benefit claim that ERISA preempts. First, I would call the lawyer on the other side and explain that ERISA preempts his order, but the plan will consider his client’s benefit claim under the plan’s claims procedures, and you can then determine if there is any basis under the plan terms for his client's claim, such as the designation being ambiguous. If that does not work, you have two litigation choices. First, respond in state court that the order is preempted under conflict preemption, and cite the above Supreme Court decisions. This, however, means one has to appeal through the state courts, if one can’t persuade the local court to withdraw its order. Second, rely on 28 U.S.C.S. § 1441(a) to remove the matter to federal court on the basis that ERISA completely preempts a state-law benefits claim, which is what the court order is seeking to achieve. See generally Metropolitan Insurance Co. v. Taylor, 481 U.S. 58 (1987). Most benefits attorneys prefer the latter approach.