Yahoo scored a victory recently when a federal court judge in California denied class certification in a Telephone Consumer Protection Act suit against the company.

Susan Pathman and Rafael Sherman failed to define an ascertainable class of individuals who allegedly received text messages from Yahoo, the court said, as they lacked an “administratively feasible” means of identifying class members. The suit targeted Yahoo’s “Welcome Message,” a text sent when a Yahoo user attempted to contact another individual on Yahoo’s online messenger service. Pathman and Sherman argued that they did not provide consent to receive the text in violation of the TCPA.

When the court denied Yahoo’s motion to dismiss the suit, Plaintiffs filed for class certification. They proposed a three-step process to ascertain the putative class. First, they would obtain Yahoo’s records from its Optin DB database, showing the time and date the Welcome Message was sent. Next, they would limit the unique mobile numbers to those assigned to certain carriers before comparing the mobile numbers listed in the database with a separate Yahoo database called UDB that contains the names, e-mail addresses, and mailing address information of account holders.

To fill any gaps, the Plaintiffs said they would subpoena carriers for information, use a reverse telephone number lookup, and/or send class notice to Yahoo e-mail accounts.

But U.S. District Court Judge Gonzalo P. Curiel agreed with Yahoo that Plaintiffs’ plan was not feasible, as they failed to demonstrate any source or combination of sources that exist to identify class members.

During discovery, Plaintiffs obtained Yahoo’s Optin DB database records as well as a complete list of mobile numbers assigned to a single carrier that received the Welcome Message over a one-month period in May 2013. But even with that sample, the Plaintiffs still lacked the names, e-mail addresses, and postal addresses of the individuals that owned those mobile numbers.

“Without this information, the class members’ identities cannot be ascertained, nor can these individuals be contacted,” the court said. “Plaintiff has not shown that her initial proposal for overcoming this hurdle—cross-referencing these phone numbers with information contained in Yahoo’s UDB—is likely to provide complete or even accurate information for class members.”

Whether Yahoo users chose to provide true names or contact information when they registered for an account was entirely voluntary, the court said, and Yahoo demonstrated multiple instances where a single mobile number was associated with multiple Yahoo accounts, either because someone miskeyed an entry or the number was later reassigned to a new user. Pathman herself demonstrated this problem, as the mobile number associated with her account was also linked to a different account, the court noted.

A reverse directory would provide minimal assistance and be of questionable accuracy, Judge Curiel wrote, adding that a subpoena to mobile carriers would also not save the day, as cellular carriers have refused to turn over similar records based on California privacy law. Emailing Yahoo users would be equally unworkable, the court added, as recipients would have to recall whether or not they received a single text message from over two years ago, and it would be highly improbable that they retained the message.

“In sum, the Court finds that even if Plaintiffs were to utilize all of these methods and attempt to cross-reference massive amounts of data to identify class members, Plaintiff still would be left with a data set of questionable reliability that covered only some unknown fraction of the putative class,” Judge Curiel said. “Plaintiff’s burden is to provide an objective, reliable, and administratively feasible method of ascertaining the class. Plaintiff has not met her burden.”

The court also found that Pathman was neither a typical nor adequate class representative. As the holder of two Yahoo accounts, Pathman agreed to the defendant’s terms and conditions on two different occasions and may have consented to receive the Welcome Message. “This profile would put Plaintiff at odds with class members in several other consent groups,” the court said, and put her “in a position of having interests that are not typical of the entire class and, thus, being preoccupied with unique defenses.”

Given all of these concerns, the court agreed with Yahoo that a class action was not superior to individual actions. Even if the Plaintiff narrowed the class to the one month for which she had some data, “Rule 23 seeks to ensure fair and efficient resolution of the controversy,” Judge Curiel wrote. “Plaintiff’s highly circumscribed class definition seems to offend the very purpose of the rule,” and Yahoo would still be subject to suit for every other month it sent the Welcome Message—and even for the same month in 2013, to the extent the phone numbers involved were assigned to different cellular providers.

To read the order in Sherman v. Yahoo! Inc., click here.

Why it matters: Yahoo dodged a class action bullet in the court’s decision, and it remains to be seen if the Plaintiffs will elect to move forward on an individual claim against the company—a seemingly cost-prohibitive move, even if they win trebled damages of $1,500 under the statute. Facing four other class actions over the Welcome Message, Yahoo will likely attempt to replicate its success by arguing that class treatment is not the superior method for resolving the dispute in those cases.