Two of the biggest online measurement companies are locked in a battle over alleged patent infringement, reports the Wall Street Journal.
ComScore and Nielsen's Netratings are the dominant online measurement sources that track the number of people and the amount of time they spend on some of the world's most popular websites such as Walt Disney's ESPN.com, Yahoo and Google.
Both companies are seeking unspecified damages and injunctive relief.
"ComScore filed a counter suit against Nielsen Holdings and its Netratings division in a United States District Court alleging infringement of patent rights, comScore revealed in a regulatory filing on on Tuesday."
"Nielsen is claiming that comScore violated its patent rights and filed a lawsuit on March 16 in a U.S. District Court."
"While we support vigorous competition in the marketplace, that competition must be fair and respect intellectual property rights," Nielsen said in a statement. "Nielsen doesn't take such matters lightly and only after thorough analysis and consideration did we file this action. We look forward to a fair and appropriate resolution."
In the government filing, comScore said it "intends to vigorously protect its intellectual property and defend itself."