Anila in the United Kingdom complains about a barrister (Lawyer to our American friends) in the lab:

Over the years I have had problem people passing through my lab at this teaching hospital and have adopted the following formula!!. Tell them:

1) Its your lab, you are in charge of it.
2) Visiting researchers/residents are to follow the lab procedures.
3) You can help them with their research only if the lab procedures are followed.
4) If they don't follow your procedures they cannot work there.
6) Do not defend anything you do in your lab to them.
7) Ask them if they have understood what you have told them.

If they say "yes", it should cure the problem. If they say "No" you had better send them to the Chairman/professor for a lttle chat. The boss will back you up because bosses understand the need for consistancy in lab procedures and research. 
Hope this helps

Mike Titford
USA Pathology
Mobile AL USA