San Jose, Calif. — In a federal court hearing for Apple’s (NASD:AAPL) trademark infringement lawsuit against (NASD:AMZN) Wednesday, District Judge Phyllis Hamilton stated that Apple would face a “stumbling block” when trying to prove users would confuse Apple’s App Store with Amazon’s App Store for Android, a source for Reuters said.

In March, Apple filed a trademark infringement claim against online retail giant, claiming its use of the term “app store” infringes on Apple’s App Store for its iOS devices.  The lawsuit says Amazon is creating confusion among consumers and engaging in unfair competition with its “Amazon Appstore Developer Portal” and related uses of the phrase.  The suit was filed days after Amazon introduced its Android Appstore, which offers nearly 3,800 apps for mobile devices running Google’s Android operating system.

Apple has filed to register “app store” as a trademark with the U.S. Patent and Trademark Office, but is facing opposition from Microsoft (NASD:MSFT), which has opposed the registration.

Related Links: (Reuters)