To hold someone legally responsible for your brain injury, you generally need to prove four things: they had a duty of care toward you (for example, drivers must watch for cyclists), they breached that duty (by running a red light or texting while driving), their breach directly caused the accident, and you suffered real damages as a result. This is the legal standard of negligence, and it applies to most bicycle-versus-vehicle TBI cases.
The driver is typically held liable for damages if a collision is caused by their negligence. However, liability must be proven by demonstrating their fault and its direct connection to your injuries.
Other parties may also be held accountable. Local governments might bear responsibility if poorly maintained roads or missing signs lead to your accident. Pursuing claims against government entities often involves specific notice requirements and may be limited by sovereign immunity laws.
The manufacturers of your bicycle or helmet could also be liable, if their products are defective and this directly contributed to the injury. These can include helmets failing to meet safety standards or bicycles with faulty brakes.