The U.S. Supreme Court on Monday refused to consider an appeal by Forest Laboratories Inc. (FRX) that sought to overturn a lower court ruling in favor of a generic drug maker that wants to market a generic version of Forest's depression drug Lexapro.

Without comment, the high court left in place an appeals court ruling that generic drug maker Caraco Pharmaceutical Laboratories Ltd. (CPD) could sue to challenge the validity of one of Forest's Lexapro patents.

Forest argued that Caraco could not bring a lawsuit because there was no legal controversy that would give the courts jurisdiction over the case. Forest said there was no legal dispute between the companies because it had agreed not to sue the generic drug maker for patent infringement.

Caraco's lawsuit now goes back to the lower courts for additional proceedings. The two companies are also engaged in another lawsuit involving a different Lexapro patent.

-By Brent Kendall, Dow Jones Newswires; 202-862-9222; brent.kendall@dowjones.com