22-year-old Tyler Burrone made his first appearance in Tehama County court Tuesday morning.
Prosecutors argue Burrone was texting and driving in July 2013 which ultimately led to the death of 5-year-old Gunner Langenderfer.
Burrone entered not guilty pleas to charges of vehicular manslaughter and involuntary manslaughter.
Investigators said Burrone was texting when he rear-ended the car carrying Langenderfer and pushed it into the path of an oncoming big rig.
Langenderfer was killed and his mother, Katie Ramsey, was seriously injured.
Investigators pulled Burrone's cell phone records from the time of the crash.
Tehama County District Attorney Gregg Cohen said this is a tough case, reminding people how deadly distracted driving can be.
"People drive with their attention directed at various things and it's a huge problem.This is the extreme outcome of that problem of inattentive driving. We need to stop texting and we need to drive," Cohen said.
Burrone is out on bail.
If convicted he could face up to six years in prison.
He will be back in court to set a date for his preliminary hearing on June 2.