Elon Musk’s X has challenged in court a €120 million fine imposed by the European Commission for breaching EU tech rules.

The fine, issued in December, was a landmark moment in the EU’s implementation of its platform rules, the Digital Services Act (DSA), and marked a point of no return in its sparring with the United States over the same rules.

“This EU decision resulted from an incomplete and superficial investigation, grave procedural errors, a tortured interpretation of the obligations under the DSA, and systematic breaches of rights of defense and basic due-process requirements suggesting prosecutorial bias,” X’s Global Government Affairs team said on the platform on Friday.

The fine was the first under the DSA and was levied due to breaches in transparency obligations and the allegedly deceptive design of X’s blue checkmarks.

Three cases were lodged against the Commission in the Court of Justice of the European Union’s docket on Feb. 16. One is from X Internet Unlimited Company and X Holdings, another from xAI Holdings and one that appears to be from tech mogul Elon Musk himself.

The Commission’s fine was addressed to all of these entities, according to a version of the decision subpoenaed and published by a U.S. congressional committee.

“This landmark case is the first judicial challenge to a DSA fine and could set important precedents for enforcement, penalty calculations, and fundamental rights protections under the 2022 regulation,” the X team said in its post.

The news was first reported by MLex.