Most people don't think twice about letting friends or family members borrow their vehicles, and most times this isn't a problem. However, you could be opening yourself up to a lawsuit if you let someone who is ill use your vehicle and that person causes an accident. Here's how you could be put on the hook for paying compensation to the victims in that situation.
If someone who was injured in an accident caused by your sick loved one learns you are the owner of the vehicle, that person could sue you using negligent entrustment laws. This tort essentially holds one party responsible for damages if he or she entrusts another party with a dangerous instrument and that second party subsequently hurts someone else using that instrument. In the case of an auto accident, you may be held responsible for damages by giving your sick friend permission to use your vehicle.
However, you can only be held responsible if you knew or had reason to know the person's illness would negatively impact his or her ability to safely operate the vehicle. For example, if your friend had an illness that caused him or her to lose consciousness on a regular basis and that person passed out while behind the wheel of the vehicle, you would be held at least partially responsible for the incident if you knew about the person's condition or his or her symptoms were so obvious that you should have been aware of the issue.
To win a case against you, the victim of the accident would have to prove that you knew the driver was too sick to drive at the time you let the person borrow your vehicle. This can be challenging depending on the circumstances of the case.
For instance, the nature of the person's illness will play a role in whether the plaintiff can make a case against you. Someone suffering from a mild cold will have different capabilities than someone who has the flu and suffering from a high temperature. Whether the person was taking medication or not may also be an issue, especially if the medication caused adverse side effects that contributed to the accident.
Another issue that will come up is the degree to which the illness contributed to the accident. If the accident would've occurred regardless of whether the driver was ill or not (e.g. multi-chain accident), then the plaintiff would have a difficult time pinning liability on you since the incident had nothing to do with the driver's competence.
For more information about this issue or help defending an auto accident case, contact an attorney.