Henry Ruggs was travelling 156 MPH seconds before the fatal crash, slamming into the back of the Toyota at 127 MPH, killing a 23-year-old woman, this according to cops.

Ruggs appeared in court this morning for the first time ... and had a gash on his face and was in a neck brace.

Cops say Ruggs -- who appeared to be impaired at the scene -- refused to participate in field sobriety tests before he was transported to the hospital.