Final answer:
After witnessing a crash involving an aggressive driver you've observed, check on the victims' welfare, call emergency services, and offer your observations to authorities. Your witness account may provide crucial information for the investigation.
Step-by-step explanation:
If you've observed someone driving aggressively and that driver is subsequently involved in a crash farther down the road, it is important to recognize your role as a witness. First and foremost, be concerned for the safety of those involved in the crash. If it is safe to do so, you should stop and check on the welfare of the crash victims, offering assistance if needed and contacting emergency services immediately.
Remember that your observations of the aggressive driving behavior prior to the accident may be valuable information for law enforcement and insurance investigators. Once the situation is stabilized and help is on the way, provide your contact information to the authorities so you can provide a witness statement when appropriate. In such scenarios, adhering to a moral obligation to offer aid and act responsibly often supersedes other considerations, much like in the ethical examples implied by figures such as William David Ross