A recent court filing by Apple with the International Trade Commission claims the Department of Justice is investigating Samsung to determine whether they have used, or misused, declared-essential patents. Bloomberg suggested such an investigation might take place as early as June which correlates with a report from NASDAQ that claim an investigation has been going on for several months.

Standard-essential patents are described as those that are necessary for a product to operate according to industry standards. Examples of this include 3G, 4G, GSM or even H.264 technology. Patents governing the use of essential technology should be made available to all market players under fair, reasonable and non-discriminatory (FRAND) terms.

Apple claims that Samsung is using key patents as the basis for unfair legal action against competitors in a bid to block the sale of certain products. Cupertino believes Samsung has violated its commitment to licensing patents on FRAND terms.

A Samsung spokesperson said the company has not received any formal notification from authorities and that they continue to remain committed to fair licensing of standard-essential patents. A spokesperson for the Justice Department declined to comment or confirm the probe. Apple also declined to comment on the story.

The situation is similar to one that Google found itself in earlier this year following their acquisition of Motorola Mobility. The Justice Department noted at the time that they would more closely monitor how companies use essential patents in the wireless industry.