Google faced a big setback Thursday in its attempt to overturn a multibillion-dollar European Union antitrust penalty involving Android after a top court's legal adviser sided with regulators.

The European Court of Justice's advocate general, Juliane Kokott, recommended in a preliminary opinion that Google's appeal against the fine worth more than 4 billion euros ($4.7 billion) should be dismissed.

The case dates back to 2018, when the EU’s executive Commission slapped Google with a 4.134 billion euro fine after finding that the US tech company used the dominance of its mobile android operating system to throttle competition and reduce consumer choice.

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After Google filed an initial appeal, a lower court trimmed the penalty to 4.125 billion euros in 2022, which the company also appealed to the Court of Justice.

Kokott advised that the Court of Justice confirm the fine and uphold the lower court's judgment, according to a press release summarising her opinion.

Opinions from the advocate general aren’t legally binding but are often followed by judges.

The judges “are now beginning their deliberations in this case. Judgment will be given at a later date,” the court said.

The fine was one of three antitrust penalties totaling more than 8 billion euros that the European Commission slapped on Google in the last decade, as the 27-nation bloc launched its crackdown on Big Tech companies.

Google still faces a decision from Brussels in an antitrust case targeting its digital ad business.