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The decade-long fight over the price of a generic epilepsy drug is not over yet. On 19 June 2026, in Pfizer / Flynn Pharma v Competition and Markets Authority [2026] EWCA Civ 765, the Court of Appeal set aside the Competition Appeal Tribunal's latest decision in the phenytoin saga — one of the most closely watched abuse-of-dominance cases in UK competition law — and sent the dispute back into uncertainty.

What the case was about

In 2022 the CMA found that Pfizer and Flynn had abused a dominant position by charging unfair prices for phenytoin sodium capsules — an anti-epilepsy drug — contrary to the Chapter II prohibition in section 18 of the Competition Act 1998. The CMA's case was that, after the drug was de-branded, its price was raised to unfair levels over the period September 2012 to December 2016 without justification.

That decision went on appeal to the Competition Appeal Tribunal. The CAT set the CMA's decision aside — but then re-made the decision itself, again concluding that Pfizer and Flynn had abused their dominance. Both the companies and the CMA were dissatisfied: Pfizer and Flynn challenged the CAT's retaken decision, while the CMA challenged the CAT's decision to set aside its original ruling in the first place.

What the Court of Appeal decided

The Court of Appeal (Lord Justices Green, Snowden and Zacaroli, in a single judgment of the Court) held that the CAT's retaken decision was vitiated by procedural unfairness and could not stand. The Court's central criticism was that, in remaking the decision, the CAT had reached conclusions on issues it had itself identified as important without giving the parties an adequate opportunity to address those issues with evidence and submissions — and had adopted an evaluative framework that pre-judged matters rather than deciding them on the best available evidence.

The disposal was sweeping. The Court:

  • granted the CMA permission to appeal, and allowed its appeal, against the CAT's decision to set aside the original CMA Decision;
  • allowed Pfizer's and Flynn's appeals against the CAT's retaken decision and set that decision aside; and
  • set aside the CAT's judgment in its entirety.

Crucially, the Court did not decide the substantive question of whether Pfizer and Flynn in fact abused their dominance. It expressly left over, for a separate ruling after further submissions, whether the CMA's original 2022 Decision should now be reinstated, together with any consequential questions about penalties.

Why it matters

This is a significant moment in a case that competition lawyers have followed for years, and the implications run wider than the parties:

  • The excessive-pricing question is still live. Nobody has "won" on the merits. By setting aside the CAT's judgment in full and parking reinstatement and penalties for a later ruling, the Court has reopened, rather than resolved, the central abuse-of-dominance issue.
  • A pointed lesson on procedure for the specialist tribunal. The judgment is a reminder that when a tribunal takes the significant step of remaking a regulator's decision itself, it must still give every party a fair chance to meet the issues on which the outcome turns. Procedural fairness is not a casualty of efficiency.
  • Continued uncertainty for unfair-pricing enforcement. Phenytoin remains one of the few fully litigated UK excessive-pricing cases. Until the follow-up ruling, the methodology for assessing "unfair" pricing under section 18 — and the fate of the CMA's findings — stay unsettled.

Watch for the Court's separate ruling on reinstatement and penalties, which will determine where this leaves Pfizer, Flynn and the CMA.

Research on Search the Law

Research the abuse-of-dominance and excessive-pricing authorities on Search the Law:

unfair pricing under the Chapter II prohibition

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