Love the lawyers?!
The whole thing boils down to someone has to be in command thus the term Pilot In Command. The legal types have to know who to go after in the event an untoward event happens. Usually in air carrier operations this is spelled out in the paperwork for the flight. Unfortunately, in general aviation it is not spelled out and sometimes you can become PIC and not realize it. Happened to a friend many years ago. Robert was a CFI and was asked to just right around the pattern a couple of times with another mutual friend. Turned out the guy who asked Robert to ride with him was not current and lost control of the aircraft on the 2nd circuit striking several taxi lights. Since Robert was the only pilot who was current and qualified he was the PIC and caught a bunch of grief.
Just be careful!
Jon