The decision is here. It was authored by Justice Alito, and Justice Sotomayor is the lone dissent. Justices Ginsburg and Breyer filed a concurrence.
In this case, we consider whether the fiduciary exception applies to the general trust relationship between the United States and the Indian tribes. We hold that it does not. Although the Government’s responsibilities with re- spect to the management of funds belonging to Indian tribes bear some resemblance to those of a private trustee, this analogy cannot be taken too far. The trust obligations of the United States to the Indian tribes are established and governed by statute rather than the common law, and in fulfilling its statutory duties, the Government acts not as a private trustee but pursuant to its sovereign interest in the execution of federal law. The reasons for the fiduci- ary exception—that the trustee has no independent interest in trust administration, and that the trustee is subject to a general common-law duty of disclosure—do not apply in this context.
And from the dissent:
Federal Indian policy, as established by a network of federal statutes, requires the United States to act strictly in a fiduciary capacity when managing Indian trust fund accounts. The interests of the Federal Government as trustee and the Jicarilla Apache Nation (Nation) as beneficiary are thus entirely aligned in the context of Indian trust fund management. Where, as here, the governing statutory scheme establishes a conventional fiduciary relationship, the Government’s duties include fiduciary obligations derived from common-law trust principles. Because the common-law rationales for the fiduciary exception fully support its application in this context, I would hold that the Government may not rely on the attorney-client privilege to withhold from the Nation communications between the Government and its attorneys relating to trust fund management.
Turtle Talk 
The decision seems to stand for the principle that trust duties and resposnibilites only exist if specifically mandated in statutes or treaties. if this is the case, why call them “trust” duties. They are only statutory duties or treaty obligations. In effect, this makes the trust doctrine an empty vessel. It’s only purpose is once again the one defined in kagama: giving more power to Congress at the expense of Indians.
The fallacy in this opinion lay in the opening premise that fiduciary trust common law is irrelevant to interpreting, defining and enforcing the statutorily mandated trust duties, obligations and responsibilities. Common law always serves as the backdrop and supplement to statutory interpretation and application, particularly when terms and concepts embedded in common law are expressed in the statutory language. The Justices were obviously desperately searching for a concocted, convoluted rationale for their desired, predetermined exculpatory outcome relieving and immunizing the US from any liability or wrongdoing for intentional and gross negligent mismanagement of trust funds which are blatant violations of normal trust obligations owed to any trust beneficiary including Indian Country People. This decisions in effect discriminates and exempts all Indian People from the standard protections of the fiduciary trust/beneficiary relationship which were subsumed in the crafting of the statutory provisions. Only the ‘intelligent’ people see that the Emperor’s new clothes. Thankfully, but impotently, the dissent points out that the King is naked. “Where, as here, the governing statutory scheme establishes a conventional fiduciary relationship, the Government’s duties include fiduciary obligations derived from common-law trust principles.”