Truck driver Ryszard Masierak has been found guilty of causing the deaths of eight people in a crash on the M1 near Newport Pagnall.
The 31-year-old had parked his truck in the inside lane of the M1 last August when he was involved in the crash with a minibus and another lorry.
Tests showed he was twice the drink-drive limit.
A jury at Reading Crown Court found Masierak, who was driving for Aim Logistics, guilty of eight counts of causing death by dangerous driving. He will be sentenced in due course. The jury is still deliberating charges against the driver of the other lorry involved in the incident, David Wagstaff.
The 54-year-old of Derwent Street, Stoke-on-Trent, denies the same charges.
Masierak's vehicle was stopped in the carriageway for about 12 minutes. The eight people killed were all travelling in the minibus. Four other passengers were seriously injured.