Qualcomm has gone to court in London to defend itself against a landmark £480 million (A$978 million) class action lawsuit alleging it used its market dominance to inflate the cost of smartphones sold by Apple and Samsung.

The five-week trial, now underway at the UK’s Competition Appeal Tribunal, has been brought by consumer advocacy group Which?.

The group claims Qualcomm’s licensing practices forced Apple and Samsung to pay excessive royalties for chip technology, which it says were passed on to consumers through higher handset prices.

At the centre of the dispute is Qualcomm’s controversial “no licence, no chips” policy that Which? argues amounts to an “industry-wide private tax” that boosts Qualcomm’s profits at the expense of consumers.

The alleged overcharging covers iPhones and Samsung Galaxy devices sold between October 2015 and January 2024.

If the case succeeds, affected consumers could receive about £17 (A$33) per device, although a second phase of the proceedings would be needed to determine any payouts, meaning compensation could still be years away.

Qualcomm denies any wrongdoing, insisting the lawsuit misrepresents standard industry practice. Its legal team argues manufacturers like Apple and Samsung hold significant bargaining power and that Qualcomm’s patent licensing terms are fair and compliant with competition law.

The lawsuit, first filed in 2021, mirrors similar antitrust battles Qualcomm has faced globally.

The chip giant has previously beaten comparable cases in the US, though it was fined in Europe over separate competition breaches.

While the UK case represents a small fraction of Qualcomm’s global business, analysts say the outcome could set a precedent for how tech licensing is regulated, and how much smartphone makers can pass on to consumers.