"An assessment of market power is the initial inquiry under the indirect method. In this case, the parties had stipulated 2013 network market shares of Visa, 45 percent, Amex, 26.4 percent, MasterCard, 23.3 percent and Discover (not a defendant here), 5.3 percent."

"(The states did not seek review of the 2nd Circuit's decision that they failed to make a prima facie case under the indirect method.)"

Have the states have conceded that Amex lacks market power?

"Gorsuch reiterated that in the absence of market power, a vertical restriction "is not within the cognizance of the antitrust laws." And, without more, a 26 percent share of a market does not constitute power."

How much direct harm can be caused by a firm that lacks market power?