As an aviation claims adjuster I can add my 2 cents. As mentioned in the thread, although the worst case scenario is always possible, in reality it doesn’t happen often.
Worst case example:
You pass a rich student, and with his wet private ticket, he takes his brand new SR22 with his wife and kid and plows it into a mountain the next week. He was a high earner, and now his remaining kid doesn’t have a family. His estate lawyers up and and is lookin to start slinging lawsuits. You are one of many defendants. Well, now the attorney will have to prove that your instruction contributed to the accident, which is an uphill battle. If you document and save your lessons and play it by the book, you have a strong defense. The plaintiff, in this case that is the estate, has the burden of proof, unless you clearly pencil whipped his checkride sign off, there won’t be a lot of proof. You taught him how to read a VFR map, pilotage and dead reckoning, so where’s the proof that you contributed in the crash? Did he fly into the clouds? Well, you taught him how to read forecasts, METARS, VFR airspace requirements, hell you taught him how to get himself out of the cloud if he accidentally flew into one. It’s all there in your lesson plans which you’ve kept and check off.
Ok so lets say the attorney sues anyway in this scenario just to force you to put money on the table to get out of the suit. This DOES happen. This is where your insurance policy comes in(get one). A liability policy also covers defense costs in addition to the liability limit. So if you have 1 million in limits, they will ALSO pay to defend you should you get sued. Plaintiff attorney knows that he will have a tough time with burden of proof, so he takes a small amount, say, $10,000 to go away. The meter is running on his end as well. Unless he has an ironclad case, he won’t spend time(and plaintiff’s money)on a losing effort.
The real world CFI liability is gear up landings. Instructor is sitting there with a student in his own plane and they belly it in. Who’s PIC? What was the nature of the instruction? But in those cases there usually comparative fault and your insurance policy(you have one, right?) will cover your arse if need be.
Please- instruct, enjoy, but get a simple liability policy. Speak with a broker for real advice. Aopa has a broker division. I do know that AIG Aviation offers instructor policies(not to be confused with USAIG, a separate, strictly aviation insurance company).