The top three drivers in the Indy Lights standings have been placed on probation for the balance of the season following last weekend's round at Road America.
Carlin's Ed Jones, Andretti Autosport's Dean Stoneman and Schmidt Peterson Motorsports' Santiago Urrutia will contest the remaining races facing "minimum 10 championship points" penalties for further indiscretions.
"The notices issued do not preclude a driver from racing hard, but serve as a reminder on how to race over the final eight rounds of the championship," Indy Lights race director Tony Cotman said.
An Indy Lights statement did not disclose the reasons for the penalties, but British drivers Jones and Stoneman clashed during the Sunday race while fighting for the lead in greasy conditions.
Jones squeezed Stoneman on the inside and onto the grass on the run between Turns 5 and 6, but Stoneman managed to edge ahead into the corner.
He then forced Jones wide, and a slowed Jones was hit from behind by team-mate Felix Serralles.
Both Carlin cars pitted with damage, while Stoneman picked up a puncture in the exchange, with Urrutia winning the race.
"There was some questionable driving out there which cost me my race and you simply can't do what some of them are doing," Stoneman said.
Jones tweeted: "Tough day. Walking away with the race in the wet until the caution came out, then got run out wide and ended up being collected."
Jones leads the championship on 213 points, with rookies Stoneman and Urrita second and third on 194 and 189 respectively.