The officers were searching for Mr. Filippidis' Florida-licensed, palm-size Kel-Tec .38 semi-automatic handgun, which he left at home locked in his safe. (Maryland does not recognize handgun permits issued by other states.)
When the search turned up nothing, Mr. Filippidis, 51, was allowed to go and was issued only a speeding warning.
The incident gained national attention. Mr. Filippidis went on multiple radio programs and described in detail how scared and outraged he and his family were. He wondered: How did the police know he was licensed for concealed carry, and what right did they have to search through his personal items on the side of the busy interstate filled with holiday travelers on that 10-degree day?
"My wife's hysterical, shaking and crying," Mr. Filippidis recalled in an interview with The Washington Times. "I don't have a criminal record. I own a business. I'm a family man, and I tried to explain that to [the officer]. But he had a bad attitude, didn't want to hear my story. He just wanted to find that gun and take me away from my family. That was his goal, but he couldn't do it, because I didn't have a gun, like I told him."
Those findings, however, have not satisfied other out-of-state gun owners, who worry that they, too, have been targeted for minor traffic stops in Maryland because they have concealed weapons permits. Their stories are accumulating.
John Tonnesen IV of Lake Worth, Florida, was pulled over and arrested after a search of his work truck — by the same officer who stopped Mr. Filippidis — turned up his .45-caliber Ruger, licensed in the state of Florida. He doesn't believe the stop was coincidental.
"It was unloaded and stuffed into a bag far from me," Mr. Tonnesen told The Times. "There's scanners in Maryland that scan every tag, and Florida is one of their target vehicles. They'll find whatever reason they can to pull you over."
MDTA denies it targets out-of-state gun owners and noted the review of Mr. Fillipides earlier traffic stop concluded the officers did nothing wrong.
"The MDTA Police conducted a review of the traffic stop and have concluded that the stop and subsequent search of the vehicle were justified," spokesman Jonathan Green wrote in an emailed statement. "The investigation did not reveal any violations of law or agency policy."
The officer who stopped both gun owners is "assigned to the I-95 corridor where there is a large volume of out of state travelers," Mr. Green said.
Baltimore-based criminal defense lawyer Paul Kramer says these type of stops and searches happen far too often in Maryland and are a waste of taxpayer money. Mr. Kramer represented a Pennsylvania security officer who was pulled over in the state for speeding.
Maryland is one of the toughest gun control states in the nation and passed the Maryland Firearm Safety Act of 2013, which, among its provisions, bans 45 assault weapons and limits gun magazines to 10 rounds.
Maryland also has strict laws governing the transportation of guns and issues concealed carry only on a "need-based" determination. Maryland does not recognize any out-of-state carry licenses.