Google suffered a significant blow on Thursday in its ongoing effort to overturn a multibillion-euro antitrust fine from the European Union, as a top legal adviser to the EU’s highest court sided with regulators.

Juliane Kokott, the advocate general of the European Court of Justice, issued a non-binding opinion recommending that Google’s appeal against the penalty—worth over 4 billion euros ($4.7 billion)—be dismissed.

The case originated in 2018 when the European Commission, the EU’s executive arm, fined Google 4.134 billion euros. The Commission concluded that Google had misused the dominance of its Android mobile operating system to suppress competition and limit consumer choices.

Google challenged the ruling, and in 2022 a lower court slightly reduced the fine to 4.125 billion euros. However, Google proceeded to appeal that decision as well, taking it to the European Court of Justice.

In her advisory opinion, Kokott recommended that the court uphold both the fine and the lower court’s ruling. Her opinion was summarized in a press release issued by the court.

Responding to the development, Google expressed disappointment, arguing that if the court accepts the advocate general’s recommendation, it could have a chilling effect on investment in open platforms. The company said this would negatively impact Android users, developers, and business partners.

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“Android has created more choice for everyone and supports thousands of successful businesses in Europe and around the world,” Google said in a statement.

Although advocate general opinions are not legally binding, they are often influential and commonly adopted by the judges in their final rulings.

The European Court of Justice confirmed that the judges have now begun their deliberations, with a final judgment to be issued at a later date.

This Android-related fine is one of three major antitrust penalties imposed on Google by the European Commission in the past decade, amounting to over 8 billion euros, as the EU intensifies its regulatory efforts against Big Tech firms.

Google also remains under investigation in Brussels in a separate antitrust case concerning its digital advertising operations, with a decision still pending.