Illinois Brick Co. v. Illinois , 431 U.S. 720 (1977)
holds that plaintiffs who directly purchase products
from an antitrust violator may sue to recover unlawful
price overcharges; whereas, indirect purchasers may not
sue. In traditional vertical distribution chains, where
the product is resold down the chain, the doctrine is
straightforward. But, Ohio v. American Express Co.,
138 S.Ct. 2274 (2018) presents a novel twist on Illinois
Brick' s rule that has enormous implications for the
antitrust laws and the national economy. It holds that
"two-sided transaction platforms" – i.e., business
models (like credit cards) that facilitate transactions
between consumers and merchants on either side of the
platform – sell transactions directly to both consumers
and merchants at the same time.
In direct conflict with American Express and
well-established antitrust precedents, the Second
Circuit in this credit card transaction fee price-fixing
case held that the petitioner cardholders do not
purchase transactions from the payment card banks. In
conflict with Apple Inc. v. Pepper , 139 S.Ct. 1514
(2019), it further held that cardholders are not direct
payors of the transaction fee, even though the banks
take the fee directly from the cardholders' payments to
merchants.
The question presented is:
Whether a consumer in a two-sided transaction
platform is a direct purchaser of transactions, where
the platform operator takes the transaction fee directly
from the consumer.

Whether a consumer in a two-sided transaction platform is a direct purchaser of transactions, where the platform operator takes the transaction fee directly from the consumer