The European Commission might have been accused of chasing fading phantoms when in 2009 it went after Microsoft for foisting its Internet Explorer browser on Windows users. Competition was already rapidly eroding Explorer’s lead. But Brussels is now right to take a stand against the group’s failure to abide by its own commitments to resolve the problem.

No other company has so consistently flouted commission antitrust decisions. In the past eight years, Microsoft has paid close to €1.6bn in fines, largely for non-compliance. The settlement of 2009, where it agreed to offer users a choice of web browsers until the end of 2014, was a sensible attempt to avoid another damaging legal battle with regulators.

But in failing to implement its own undertakings, Microsoft is putting these accords to the test. This is the first violation since the commission acquired the power to withhold infringement proceedings in favour of such deals in 2004. Brussels’ response will determine whether in future other companies feel compelled to abide by their promises and, in consequence, whether settlements prove to be effective regulatory tools.