Today Google filed a civil lawsuit against a number of illegal online pharmacies, claiming that the businesses violated the search engine's advertisement policy.

Michael Zwibelman, Google's Litigation Counsel, wrote in a post on the company's blog that it has been battling these illegal online pharmacies for years in an effort to keep advertisements promoting illegal and fake pharmaceutical products from appearing when search results are displayed.

"It’s been an ongoing, escalating cat-and-mouse game—as we and others build new safeguards and guidelines, rogue online pharmacies always try new tactics to get around those protections and illegally sell drugs on the web," Zwibelman wrote.

Zwibelman said that in recent years Google has noticed an increase in the number of illegal online pharmacies that are becoming more sophisticated in their efforts to appear in search results. He said despite an exhaustive verification process, keyword blocking and changing its advertisement policies "a small percentage of pharma ads from these rogue companies" continue to show up in Google.

In response to these problems Zwibelman said that Google has filed a lawsuit against these illegal online pharmacies.

"This morning we filed a civil lawsuit in federal court against advertisers we believe have deliberately broken our rules," he wrote on the blog.

Zwibelman added that this lawsuit will act as a major deterrent to those who would attempt to advertise on Google illegally and that as more violators are identified they will be added to the lawsuit.

"Rogue pharmacies are bad for our users, for legitimate online pharmacies and for the entire e-commerce industry—so we are going to keep investing time and money to stop these kinds of harmful practices," he wrote.

It is not the first time that Google has taken unscrupulous advertisers to court. In December 2009, the search engine sued a number of advertisers who were promoting work-at-home schemes, according to TechEye.net.

A recent study by security software provider Symantec found that about 21 percent of all spam involves pharmaceutical products and services.

Americans are protected from illegal online pharmacies when they purchase their prescription drugs from a licensed brick-and-mortar pharmacy or from online pharmacies that have been certified by the Verified Internet Pharmacy Practice Sites, or VIPPS, program. Consumers can use legitscript.com to verify their choice of online pharmacy.