This is the second of a three-part column. The first part was published on Monday and the third part will be published on Wednesday.Tagged for $31 million in damages based on medical malpractice that destroyed both of Kevin Clanton’s kidneys, the federal government claimed a partial setoff —based on the Illinois collateral source doctrine — for the portion of his dialysis treatment that is covered by Part B of Medicare and funded by general tax revenue.Because Clanton sued under the Federal Tort Claims …