Who can give me info about UA spikes?

I have a husband in a treatment facility, since he has been there his numbers have gone up on two occassions. He is recieving punishment for this as his case manager is saying it was new use even though he has not left the facility once. Now I'm not a novice to the world of smoking so I know that body weight and many other factors can cause this to happen, but it's not new use. Where can I find the medical or scientific documents that support that fluid intake, increase in exercise and a persons own body chemistry determines elimination of the THC. Is there a way for them to re-test the sample to determine if it was new use or Metabolites stored in the fat cells being eliminated? He will be taking the info to a grievance hearing so I really need something I can print. Thanks for any help.