This is the case where John Bogle submitted an amicus brief.
The opinion is http://www.supremecourt.gov/opinions/09pdf/08-586.pdf
Looks like a mixed bag; they overturned a lower court ruling requiring plaintiffs to demonstrate that an advisor had to mislead directors.
The most relevant part to us seems to be:
The Court resolves the parties’ disagreements on several important questions. First, since the Act requires consideration of all relevant factors, §80a–35(b)(2), courts must give comparisons between the fees an investment adviser charges a captive mutual fund and the fees it charges its independent clients the weight they merit in light of the similarities and differences between the services the clients in question require. In doing so, the Court must be wary of inapt comparisons based on significant differences between those services and must be mindful that the Act does not necessarily ensure fee parity between the two types of clients. However, courts should not rely too heavily on comparisons with fees charged mutual funds by other advisers, which may not result from arm’s-length negotiations. Finally, a court’s evaluation of an investment adviser’s fiduciary duty must take into account both procedure and substance.Where disinterested directors consider all of the relevant factors, their decision to approve a particular fee agreement is entitled to considerable weight, even if the court might weigh the factors differently. Cf. Lasker, 441 U. S., at 486. In contrast, where the board’s process was deficient or the adviser withheld important information, the court must take a more rigorous look at the outcome.