Last month's $4.5 billion sale of Nortel's patent portfolio faces a tougher time from government watchdogs than the cartel buying it thought. The patents were bought by Microsoft, Apple,  Ericsson, Microsoft, Research In Motion, and Sony in a move which could prove a major headache for Google and Android.

The Wall Street Journal reports that the U.S. Department of Justice is "intensifying" an investigation of the portfolio buyers to see whether they plan on launching litigation against competitors, specifically ones using Google's Android. That deal got approval from courts in both the U.S. and Canada (where Nortel is headquartered) on July 11.

The Justice Department is interviewing the winning companies to see if they plan on filing suits against other handset makers using Google's Android operating system software. If they are then the DoJ could tell them that they can't.