If one is charged with the illegal cultivation of marijuana, a defense can be that the cultivation was entirely legal. However, the facts necessary for determining this must be provided to the judge (if a bench trial) or the jury if a jury trial. An expert in the cultivation of marijuana must usually testify as the methods and manner of cultivation calls for information above or beyond common knowledge of an average juror. What must such an expert know? Click on the following link to read about a case where these issues were put to the test.
http://www.greghillassociates.com/medical-marijuana-cultivation-expert-disqualified-at-trial.html.