SCOTUS rules AmEx didn't break antitrust laws by discouraging merchants' promotion of rival cards, in win for firms like Amazon operating in “two-sided” markets
and Silicon Valley, too
Context & Ripple Effects
Months before the ruling, coverage warned that an Amex win would let tech giants claim no consumer harm while engaging in anti-competitive conduct in two-sided markets. The Court took exactly that path: merchants who pay higher swipe fees and are barred from steering customers to cheaper cards lost, because the majority framed cardholders as the relevant side of the market.
That framing is why Silicon Valley cared — platforms like Amazon sit between two customer groups just as AmEx does between merchants and cardholders. The decision became a standing defense in the antitrust wave that followed, including the FTC's suit against Amazon, where judges have since split: granting a partial dismissal of the FTC's monopoly claims while letting core claims proceed.
First-order effects
- AmEx keeps its merchant rules intact, and every card network operating similar no-steering provisions gains the same shield against antitrust challenge.
- Merchants lose their strongest legal theory for pushing back on swipe fees and card-promotion restrictions, leaving them to absorb costs or fight contract terms commercially rather than in court.
Second-order effects
- Amazon and other platform operators can now cite the two-sided-market framework when defending pricing and seller policies — a template visible in the FTC case, where a federal judge allowed the monopoly claims to advance but trimmed state-law counts.
- State-level enforcers step into the gap: Washington, DC's revived suit over Amazon's pricing policies shows plaintiffs testing theories that survive where the federal no-harm-to-one-side logic does not.
Third-order effects
- Antitrust enforcement bifurcates by market structure: conduct on one side of a platform can be judged harmless even as the other side pays, pushing regulators toward consumer-welfare tests that platforms can satisfy by subsidizing users.
- If the pattern holds, the decisive battleground shifts from whether big platforms harm competition to how each side of the market is defined — making judicial interpretation of 'the market' more consequential than the statutes themselves.
The trend: US antitrust law is being reshaped around two-sided platforms, with the AmEx precedent serving as the reference point for every major case against Big Tech since.