Ashish Mahendru of Mahendru PC in Houston, who represented Paranjpe & Mahadass in the dispute.

With hard-to-pronounce partner surnames like Paranjpe and Mahadass at one Houston firm and Mostaghimi and Papapavlou at another, it's not surprising that the two personal injury firms would use the initials P and M in their firm names.

But the use of the similar-sounding names prompted the filing of a trademark dispute last year—one that hs now resulted in a summary judgment ruling by a Houston judge finding that Paranjpe & Mahadass did not commit any trademark infringement against PM Law Firm.

In the Feb. 3 order, 152nd District Judge Robert Schaffer of Harris County found that PM Law firm does not have a valid common law trademark for the name PM Law.

For the last several years, Paranjpe & Mahadass has used the domain name www.pandmllp.com, and P&M or PM for marketing, and P&M Law on its website. The domain name of the other firm, PM Law Firm, is www.pmtxlaw.com.

Plaintiffs lawyer Ashish Mahendru, a name partner at Houston's Mahendru, said the summary judgment brings an end to the litigation. It is unclear whether PM Law Firm will appeal.

Mahendru said Schaffer's ruling sets a precedent.

“It's a case of first impression because it is rare to find law firms trying to box out other law firms using names,” he said. “I think the disciplinary rules prohibit us from using trade names for marketing ourselves, so we are really limited to our own names.”

The partners at defendant PM Law Firm are Porya Mostaghimi and John Papapavlou. The partners at Paranjpe and Mahadass are Tej Paranjpe and Raj Mahadass.

The dispute began in May 2017, when a lawyer for PM Law Firm sent Paranjpe & Mahadass a demand letter, alleging a violation of the firm's trademark, and asking the firm to cease all use of P&M Law and the domain name. In response, Paranjpe & Mahadass filed Paranjpe & Mahadass v. PM Law Firm, seeking a declaratory judgment that it had not infringed on any common law trademark of the defendant, that the defendant's mark is not protectable, and that any marks the defendant alleges are common law trademarks that have been canceled.

In an answer, PM Law Firm sought a take-nothing judgment and damages for trademark infringement.

David Mestemaker, a partner at Mestemaker & Straub in Houston who represented defendant PM Law firm, could not immediately be reached for comment.