Samsung, the defendant in a lawsuit filed by Microsoft earlier this year in New York federal court over nearly $7 million in interest from delayed patent royalty payments, is now arguing that it was no longer bound to an agreement once Microsoft acquired phone manufacturer Nokia.

Doing so would “invite charges of collusion” from antitrust regulators, Samsung lawyers wrote in a court filing, Reuters reported.

Microsoft sued Samsung claiming that the South Korean tech company breached a 2011 agreement that called for Samsung to pay Microsoft royalties for a patent license covering Samsung-made phones running Google’s Android operating system.

The deal also called for the two companies to collaborate on Windows phones and for patent payments to drop if Samsung “met certain sales goals for Windows” phones, according to Reuters.

Windows phones failed to gain any traction in the market, producing sales below expectations of both firms.

When Microsoft acquired Nokia in April, Samsung stopped making payments as it considered the Redmond company a direct hardware competitor. Microsoft went to court to collect the $6.9 million it says Samsung “owes in interest on more than $1 billion in patent royalties it delayed paying,” Reuters reported.

Samsung’s legal argument is that it anticipated problems with U.S. antitrust laws if it continued to collaborate with Microsoft. “(T)he agreements, now between competitors, invite charges of collusion,” according to the filing. However, antitrust regulators in the U.S. and other countries have approved Microsoft’s Nokia acquisition.

Microsoft has responded via statement that it believes it has a “strong” case and would prevail. It wasn’t immediately known when the judge would rule on Samsung’s filing.