Police were called at 3.30am on June 25 following a collision in Okehampton.
A car overturned on Kellands Lane blocking the road. A second car was also damaged.
Fire and ambulance also attended.
The driver was taken to hospital with a suspected head injury.
A man in his 40s from Okehampton was arrested on suspicion of drink driving. He was later de-arrested while officers await the outcome of medical tests. Enquiries continue into this matter.