No  offense but this is really a naive conversation

A license that garuntees refunds if proven invalid would need to be purchased at a cost that would equal a large portion of the litigation expense.

In basic business terms it would be an option to sell the license back or an insurance program.

Based on the theories of market equilibrium teh licensee could simoply contact Lioyds of London and purchase an insurance contract on the validiy of the patent or consequently the licensor can do the same as a protection against invalidity. Either way the licensee would bare the cost of the insurance poilicy either directly or through an upcharge

But this is not late night TV.  buy a license or get sued. if you thnk the license is invalid then don't buy.

This whole conversaiton is ridiculous. A five minute internet search would show that  even the largest of fees paid by parties not involved in tthe litigation  for patents that were eventually overturned were not overturned.

So can we just give it a break. Agoracom is slow enough as it is without all these ridiculous postings