Lawyers said their client, a college student in Tacoma, Wash., got E. coli in May by eating a salad in her college cafeteria.
The food supplier said the lettuce was from the Salinas Valley.
Previous E. coli outbreaks that spread across the country were linked back to the Salinas Valley in 2006.
Lawyers for the case said the previous outbreaks are not the only reasons they suspect Salinas of supplying tainted lettuce.
"It is hard evidence," said Drew Falkenstein, a lawyer for the student, Heather Whybrew. "It is evidence in the outbreak investigation that led us to that conclusion."
Falkenstein said federal and state health officials have linked Romaine letter, possibly grown in the Salinas Valley, to the E. coli outbreak that sickened 10 people in May.
Whybrew spent 20 days in the hospital after being sickened by the tainted produce. She experienced pneumonia, blood clots and kidney problems.
Falkenstein refused to name the farms suspected of delivering the tainted produce.
"We do have suspicions," Falkenstain said. "At this point, I'd just like to wait until we have more concrete information."
Dennis Donohue, the chairman for the Grower-Shipper Association, said Whybrew ate her meals in a cafeteria, meaning E. coli could have worked its way into the food in other ways.
"There's so many variables with these types of incidents," Donohue said. "Who was the handler, what did the cold chain management look like in this scenario."
Falkenstein said he wants compensation for his client and change in the produce industry.
Donohue said the changes Falkenstein is asking for are being addressed and there has been no direct link between E. coli and the Salinas Valley in this case.
"We'll be quick to cooperate as an industry, as a valley and as trade groups, but we'll be equally quick to say, as we've seen in the recent weeks and months past, there have been a lot of false alarms," Donohue said.