TechCrunch is reporting that France has levied a $166 million fine against Google over abusing its online advertising dominance.

France’s competition watchdog, Autorité de la concurrence, announced the fine last week following an investigation dating back several years. The fine is based on advertising rules that were “opaque and difficult to understand” and that Google was applying in “an unfair and random manner.”

The case was brought to the competition authority’s attention over four years ago when Google closed the Google Ads account of a company called Gibmedia without any notice. Google told TechCrunch GibMedia’s account had been closed to protect consumers, as it was “running ads for websites that deceived people into paying for services on unclear billing terms.”

Autorité de la concurrence pointed out, however, that Google is not applying that rationale uniformly and currently has other sites selling similar services.

Google has vowed to fight the decision. In the meantime, in order to comply with the Autorité de la concurrence’s ruling, Google must clarify its rules and procedures, set up a warning system to alert advertisers and help them avoid account suspensions and “organize mandatory annual training for Google Ads support staff.”