I always enjoy these discussions.
Every now and then, someone ignores a request from a FAA Inspector calling to follow up about some incident, occurrence, accident or "possible" pilot deviation (PD) 8020-17, or says, "I will only talk to you through my lawyer".
Think about this. This may be the only chance you get to talk to a pilot, as all Ops Inspectors are. They speak your lingo, have probably seen or done the same thing many times themselves in a previous life. 95%+ can get handled with little muss or fuss by showing a compliant attitude.
I would wager before you get a call from an Inspector, they already have everything they need to proceed with an enforcement, should they decide to go that direction. Before that decision is made, they want to hear your side of the story. You are very rarely in jeopardy of raising an investigation to a full blown enforcement with your statement, only mitigating it down to an administrative action as R&W said earlier in this thread.
As R&W also stated, attitude weighs heavily on how the Inspector uses the latitude afforded them during the investigation stage. Tell the Inspector to pound sand, and you will most likely find the Inspector has a big sand box and an even bigger hammer with which to pound sand into places you never imagined. Cooperate, and more often than not, the Inspector will decide just a conversation will get compliance and safety is served and the case is closed.
Or in simpler words, if the event (PD) can be handled at the Inspector level, it is easier on everyone involved. Make it Inspector work hard, involve the Regional Council etc. they will tend make it worth their while. Once the Inspector is forced to start an Enforcement Investigative Report (EIR) it is out of their hands and takes on a life of its own. Lawyers get to do their lawyer thing. As you may surmise, most Inspectors don't want to get lawyers involved (yours or theirs) and keep it between pilots, abet one that works for the administrator.
Another thing to think about. A lawyer costs money. Win or loose, the Barrister gets his fee. One fellow, who did not rely on his ticket for a living, told me later he spent $12,000 dollars on his case (which the FAA had already waived the 15 day suspension sanction before going before the NTSB ALJ on appeal, for a timely NASA report) to take his appeal through the full board, which he lost again. That is not taking into account insurance hits for years to come.
As it was related to me early in my aviation career, arguing with the FAA is like wrestling with a mean old mama pig, you are going to loose and the pig likes it. Cooperate, graduate I always say.