If you have an accident without being under the influence of marijuana, can they charged you for a marijuana DUI even though it was about 2 or 3 weeks ago when you smoked ? Can you refuse to a blood test? will they test you after an accident for no reason ?
Can they charge you, yes. Whether they can convict you is another story. I don't practice in AZ so I can't answer your state's requirements for refusal or testing after the accident, but I can tell you that all DUI laws require you to actually be under the influence of the drug/alcohol at the time of driving. You should talk to an attorney in your area right away.
Lawsuit / Dispute Attorney
There may well be valid defenses available to you so get a well qualifed criminal defense lawyer on your side to act as your advocate as soon as possible. I agree with the observation of Mr. Epifanio. Good luck to you.
NOTE: This answer is made available by the lawyer for educational purposes only. By using or participating in this site you understand that there is no attorney client privilege between you and the attorney responding. This site should not be used as a substitute for competent legal advice from a licensed professional attorney that practices in the subject practice discipline and with whom you have an atttorney client relationship along with all the privileges that relationship provides. The law changes frequently and varies from jurisdiction to jurisdiction. The information and materials provided are general in nature, and may not apply to a specific factual or legal circumstance described in the question.