Google has had some luck in the courts when it comes to selling ads with trademarked keywords, but European companies buying those keywords may soon face some hurdles. An advocate general to the European Court of Justice has recommended that restrictions be placed on the use of keywords owned by other companies, though Google itself will likely remain free of liability.

Advocate general Niilo Jääskinen issued his opinion as part of a legal case between flower delivery service Interflora and Marks & Spencer, which runs a competing flower operation. Interflora had sued Marks & Spencer after Google searches for Interflora began turning up ads for Marks & Spencer, which Interflora argues is confusing to consumers and ultimately leads to lost business.

According to Jääskinen, the owner of a trademarked term should be able to prohibit other companies from using the trademarked term when the ad in question "does not enable an average Internet user, or enables the said user only with difficulty, to ascertain whether the goods or services referred to in the ad originate from the proprietor of the trade mark or an undertaking economically connected to it or from a third party."

Put more simply, if the ad makes it difficult for a regular person to figure out who's selling the advertised service, it should be prohibited.

An advocate general's opinion is not the final word, so the court is still left to make its final decision (which is expected to come within the next six months). If the court does adopt Jääskinen's recommendation, however, companies will have to be more cautious about whose trademarks they're using in their own ads, and how they are using those trademarks. If I am an Ars Technica competitor, for example, I might be able to say I'm an alternative to Ars Technica in my AdWords, but I probably wouldn't be able to imply that I am Ars Technica.

So far, however, courts in both Europe and the US have avoided holding Google itself liable for AdWord trademark abuse. Last year, the European Court of Justice ruled that the sale of trademarked keywords should be left open to third parties. That ruling came in response to a lawsuit filed by Louis Vuitton arguing that Google didn't have the right to sell Louis Vuitton keywords to others. Just a month later, a US district judge issued a similar ruling, finding that Google was not infringing on Rosetta Stone's trademark by selling its keywords to third parties.

The courts do seem to be solidly on Google's side, but Google does have policies to fight the advertisement of counterfeit goods on AdWords. (Google makes an effort to bar companies whose websites sell obvious copies or knock-offs of other products, which is a separate policy from its normal trademark rules.) In fact, the company recently added several more measures in order to keep counterfeits out, like working closer with brand owners to identify infringers. Google also says it will reduce its average response time to 24 hours for counterfeit complaints, and has rolled out a new page for reporting counterfeits.

Google didn't comment directly on the advocate general's opinion, but did say that the company thinks users are better serviced by seeing ads "for a wide variety of different contexts" that are informative and relevant to their searches. “We also believe that consumers are smart and are not confused when they see a variety of ads displayed in response to their search queries," Google told the New York Times.