We’re well used to tech companies suing one another for patent violations (and likely passing the legal bills on to us in higher prices.) But now the tables may have turned, with the European Union investigating whether Samsung misuses its own patents.

In recent years, Samsung and Apple in particular have been engaged in a patent war of attrition, both suing one another in several countries, as well as using the newer tactic of trying to get the United States International Trade Commission to block imports of the relevant devices.

It’s only fair to note that the legal action has been far from one-sided. One lawsuit by Apple over the Galaxy Tab effectively argued that if you produce a tablet, you need to make it a colorful pyramid with dozens of buttons to avoid infringement.

However, the formal EU investigation covers events dating back to the development of the 3G standard. While helping set up the standard in Europe — a standard that allowed Samsung, like other companies, to benefit from the smartphone boom — manufacturers agreed to license the patented technologies they developed relating to the standards.

That agreement recognizes the rights held by companies in their patents, but says they must license them to rival companies in a “fair, reasonable and non-discriminatory” manner. These rules only apply to patents specifically linked to the 3G standards.

After a preliminary investigation, the EU now believes Samsung may have breached those rules: indeed, that rather than licensing the patents as required, it’s used them as a weapon in lawsuits. Officials believe this may constitute an unfair attempt to distort the market by making it harder for the rival firms to compete.

Patent expert Florian Mueller notes that the opening of a formal investigation likely means the EU has received hard evidence of potential abuse during its initial probe. Mueller also notes that Apple shouldn’t fear a similar investigation for the simple reason that it rarely if ever takes part in standards development, let alone agrees to related licensing terms.

It appears the investigation is being made a priority to avoid the risk that Samsung prevails in one of the lawsuits, only for EU officials to decide too late that such lawsuits should never have been brought.