Apple on Friday sued Motorola claiming the Droid smartphone maker infringes on three iPhone patents.
Apple's filing with the U.S. District Court for the Western District of Wisconsin accuses Motorola of using Apple's touchscreen software, as well as other display technologies.
Apple's suit comes less than one month after after Motorola had sued Apple in Delaware court asking a judge to declare it is not infringing on certain Apple software patents.
Patent lawsuits are a regular occurrence among technology giants. Microsoft filed suit against Motorola in last month, accusing the company of violating its patents in mobile phones powered by Google's Android operating system. Apple has been also sued by Finnish mobile phone giant Nokia for patent infringement and has fired back with a countersuit against Nokia.