Did the Supreme Court get the market definition correct in the Amex case?

The Supreme Court is winding down for the year and last week put out a much awaited decision in Ohio v. American Express. Some have rung the alarm with this case, but I think caution is worthwhile. In short, the Court’s analysis wasn’t expansive like some have claimed, but incomplete. There are a lot of important details to this case and the guideposts it has provided will likely be fought over in future litigation over platform regulation. To narrow the scope of this post, I am going to focus on the market definition question and the issue of two-sided platforms in light of the developments in the industrial organization (IO) literature in the past two decades.

Just to review, Amex centers on what is known as anti-steering provisions. These provisions limit merchants who take the credit card payment from implying a preference for non-Amex cards; dissuading customers from using Amex cards; persuading customers to use other cards; imposing any special restrictions, conditions, disadvantages, or fees on Amex cards; or promoting other cards more than Amex. Importantly, these provisions never limited merchants from steering customers toward debit cards, checks, or cash.

In October 2010, the Department of Justice (DoJ) and several states sued Amex, Visa, and Mastercard for these contract provisions, and Amex was the only one among the three to take it to court. Initially, the District Court ruled in favor of the DoJ and states, explaining that the credit card platforms should be treated as two separate markets, one for merchants and one for cardholders. In that analysis, the court cleaved off the merchant side and declared the anti-steering provisions as being anticompetitive under Section 1 of the Sherman Act.

On appeal, the Court of Appeals for the Second Circuit reversed that decision because “without evidence of the [anti-steering provisions’] net effect on both merchants and cardholders, the District Court could not have properly concluded that the [provisions] unreasonably restrain trade in violation” of Section 1 of the Sherman Act. The Department of Justice petitioned the Appeals Court to reconsider the case en banc, but that was rejected and then headed to the Supreme Court.

The Supreme Court agreed with this two-sided theory as “credit-card networks are best understood as supplying only one product—the transaction—that is jointly consumed by a cardholder and a merchant.” Even though the DoJ was able to show that the provisions did increase merchant fees, “evidence of a price increase on one side of a two-sided transaction platform cannot, by itself, demonstrate an anticompetitive exercise of market power.” To prove this, the DoJ would have to prove that Amex increased of the cost of credit-card transactions above a competitive level, reduced the number of credit-card transactions, or otherwise stifled competition in the two-sided credit-card market.

The decision only briefly mentions why this is important, so consider a platform with two sides, users and advertisers. If users experience an increase in price or a reduction in quality, then they are likely to exit or use the platform less. Yet, advertisers are on the other side because they can reach users. So in response to the decline in user quality, advertiser demand will drop even if the ad prices stay constant. The result echoes back.  When advertisers drop out, the total amount of content also recedes and user demand falls because the platform is less valuable to them. Demand is tightly integrated between the two side of the platform. Changes in user and advertiser preferences have far outsized effects on the platforms because each side responds to the other. In other words, small changes in price or quality tends to be far more impactful in chasing off both groups from the platforms as compared to one-sided goods. In the economic parlance, these are called demand interdependencies. The demand on one side of the market is interdependent with demand on the other. Research on magazine price changes confirms this theory.   

In the last two decades, economics has been adapting to the insights and the challenges of two-sided markets. In the case of a one-sided business, like a laundromat or a mining company, there is one downstream or upstream consumer, so demand is fairly straightforward. But platforms are more complex since value must be balanced across the different participants in a platform, which leads to demand interdependencies.

In an article cited in the decision, economists David Evans and Richard Schmalensee explained the importance of their integration into competition analysis, “The key point is that it is wrong as a matter of economics to ignore significant demand interdependencies among the multiple platform sides” when defining markets. If they are ignored, then the typical analytical tools will yield incorrect assessments.
While it didn’t employ the language of demand interdependencies, the Court did agree with that general assessment:

To be sure, it is not always necessary to consider both sides of a two-sided platform. A market should be treated as one sided when the impacts of indirect network effects and relative pricing in that market are minor. Newspapers that sell advertisements, for example, arguably operate a two-sided platform because the value of an advertisement increases as more people read the newspaper. But in the newspaper-advertisement market, the indirect networks effects operate in only one direction; newspaper readers are largely indifferent to the amount of advertising that a newspaper contains. Because of these weak indirect network effects, the market for newspaper advertising behaves much like a one-sided market and should be analyzed as such.

Why does this bit matter?

In a piece in the New York Times in April, Law scholar Lina Khan worried that this case would “effectively [shield] big tech platforms from serious antitrust scrutiny.” Law professor Tim Wu followed up with an op-ed just this past week in the Times expressing similar concern,

To reach this strained conclusion, the court deployed some advanced economics that it seemed not to fully understand, nor did it apply the economics in a manner consistent with the goals of the antitrust laws. Justice Stephen Breyer’s dissent mocks the majority’s economic reasoning, as will most economists, including the creators of the “two-sided markets” theory on which the court relied. The court used academic citations in the worst way possible — to take a pass on reality.

Respectfully, I have to disagree with Wu’s assessment and Khan’s worries. Both Google and Facebook more evidently fall into the newspaper category than the payments category under the majority’s opinion. Moreover, the opinion didn’t define what “weak indirect network effects” actually means in practice, so this case doesn’t leave Google and Facebook off the hook by any means.

How the Court reached that conclusion is worth exploring, however.

In contrast to newspapers, credit card payment platforms “cannot make a sale unless both sides of the platform simultaneously agree to use their services,” so, “two-sided transaction platforms exhibit more pronounced indirect network effects and interconnected pricing and demand.” The Court seems to connect two-sidedness with the simultaneity requirement. On this front, Wu is correct. They didn’t seem to fully understand the economic reasoning. It isn’t the simultaneous nature of credit cards that makes them two-sided markets, but their demand interdependencies. Newspapers also have strong demand interdependencies even though they may not feature the simultaneity of credit cards. Yet, the Court was correct in defining the market as a transactional one, where cardholders and merchants are intimately connected.

That being said, Breyer’s economic reasoning isn’t any sharper than the majority’s:

But while the market includes substitutes, it does not include what economists call complements: goods or services that are used together with the restrained product, but that cannot be substituted for that product. See id., ¶565a, at 429; Eastman Kodak Co. v. Image Technical Services, Inc., 504 U. S. 451, 463 (1992). An example of complements is gasoline and tires. A driver needs both gasoline and tires to drive, but they are not substitutes for each other, and so the sale price of tires does not check the ability of a gasoline firm (say a gasoline monopolist) to raise the price of gasoline above competitive levels. As a treatise on the subject states: “Grouping complementary goods into the same market” is “economic nonsense,” and would “undermin[e] the rationale for the policy against monopolization or collusion in the first place.” 2B Areeda & Hovenkamp ¶565a, at 431.

Here, the relationship between merchant-related card services and shopper-related card services is primarily that of complements, not substitutes. Like gasoline and tires, both must be purchased for either to have value. Merchants upset about a price increase for merchant related services cannot avoid that price increase by becoming cardholders, in the way that, say, a buyer of newspaper advertising can switch to television advertising or direct mail in response to a newspaper’s advertising price increase.

Breyer makes a bit of a mess when it comes to the idea of demand complementarity. It isn’t the case that “both must be purchased for either to have value.” That is perfect complementarity, which is rare. Rather, when the price of gasoline increases, then the demand for tires is likely to decrease as well. However, it doesn’t need to run the other way. When the price of tires decreases, the demand for gasoline doesn’t typically inch up. This kind of asymmetric demand relationship is counter to the kind of relationship on platforms where demand in linked on both sides.

Still, Breyer buries the lede. Attributing a price increase to firms in the tire market might be wrong if demand fluctuations in the adjacent gasoline market partially caused those prices changes. In other words, the reason why complementary demand matters in the first place is to ensure that the court’s analysis is correct. Going back to Evans and Schmalensee, “The key point is that it is wrong as a matter of economics to ignore significant demand interdependencies among the multiple platform sides” when defining markets. You get the assessments wrong.

To his credit, Breyer does rightly point out the thin definition offered by the majority:

I take from that definition that there are four relevant features of such businesses on the majority’s account: they (1) offer different products or services, (2) to different groups of customers, (3) whom the “platform” connects, (4) in simultaneous transactions.

Having simultaneous transactions isn’t the defining feature of two-sidedness and if the lower courts come to rely on this feature to define platforms, then some assessments of competitive effects are likely to be wrong.

Amex offers up a lot for the antitrust community to consider, but in key ways, the decision is incomplete. Importantly, the Court didn’t address the validity of many new analytical tools that have popped up in the past decade to understand platform market power. Take a quick glance at the papers cited in the majority opinion and you will notice how many of references dates from after 2010 when this case was first brought. In other words, Amex hardly shuts the door for future litigation.