If asked "have you ever been arrested the answer is yes no matter what the outcome ...
If the question is have you ever been convicted of a crime thats another story .
Its unfair but thats the way airlines do it .

I answered Yes to a Have you ever had a 709 ride and that killed my interview chances at a regional even though the 709 ride was due to an investigation of a Designated examiner and nothing I did wrong .I still could not even get a chance to explain it . Life is very unfair .