It looks like Mozilla is heading to court for a showdown with Yahoo Holdings and Oath over an alleged breach of contract.

Yahoo Holdings and Oath, the company that runs the Yahoo search engine and which is owned by Verizon, filed a complaint against Mozilla with the Superior Court of California on Dec 1, after Mozilla revealed it was changing its default search engine. Today, Mozilla announced it was fighting back by filing a counter complaint.

The story so far

Mozilla unveiled its new lightning-fast Firefox Quantum browser three weeks ago, and the reception has been one of widespread adulation. Firefox, it seemed, was back with a bang. But alongside the launch, the company announced that it was ditching Yahoo as its default search engine in favor for the infinitely more popular Google. Mozilla, you see, had inked a deal with Yahoo in 2014 to make it the default search engine in the U.S for a full five-year period.

Though users can switch their default search engine manually, having a search engine featured by default on a major browser like Firefox has a sizeable impact — five months after the Mozilla / Yahoo deal was inked, Yahoo said that its search volume reached a five-year high. And Google became pretty desperate to get people to switch their default search engine back — even placing messages at the top of search results.

Last year, as Yahoo was preparing to sell to Verizon, a notable clause in the contract between Mozilla and Yahoo emerged. It effectively committed the acquiring company to pay Mozilla $375 million per year through 2019 if Mozilla wasn’t pleased with its new partner….

Continue ….