More information on expert witnesses
Referrals to other experts and court services

Why and how to use an expert witness
(PDF file dowload of trifold brochure -- 52k)

California EVIDENCE CODE SECTION 720-723 720.
(a) A person is qualified to testify as an expert if he has special knowledge, skill, experience, training, or education sufficient to qualify him as an expert on the subject to which his testimony relates. Against the objection of a party, such special knowledge, skill, experience, training, or education must be shown before the witness may testify as an expert. (b) A witness' special knowledge, skill, experience, training, or education may be shown by any otherwise admissible evidence, including his own testimony.

Evidence Code 721. (a) Subject to subdivision (b), a witness testifying as an expert may be cross-examined to the same extent as any other witness and, in addition, may be fully cross-examined as to (1) his or her qualifications, (2) the subject to which his or her expert testimony relates, and (3) the matter upon which his or her opinion is based and the reasons for his or her opinion. (b) If a witness testifying as an expert testifies in the form of an opinion, he or she may not be cross-examined in regard to the content or tenor of any scientific, technical, or professional text, treatise, journal, or similar publication unless any of the following occurs: (1) The witness referred to, considered, or relied upon such publication in arriving at or forming his or her opinion. (2) The publication has been admitted in evidence. (3) The publication has been established as a reliable authority by the testimony or admission of the witness or by other expert testimony or by judicial notice. If admitted, relevant portions of the publication may be read into evidence but may not be received as exhibits.

Evidence Code 722. (a) The fact of the appointment of an expert witness by the court may be revealed to the trier of fact. (b) The compensation and expenses paid or to be paid to an expert witness by the party calling him is a proper subject of inquiry by any adverse party as relevant to the credibility of the witness and the weight of his testimony.

California Evidence Code 789. Evidence of his religious belief or lack thereof is inadmissible to attack or support the credibility of a witness.

California Penal Code 867. While a witness is under examination, the magistrate shall, upon motion of either party, exclude all potential and actual witness who have not been examined. The magistrate shall also order the witnesses not to converse with each other until they are all examined. The magistrate may also order, where feasible, that the witnesses be kept separated from each other until they are all examined.
This section does not apply to the investigating officer or the investigator for the defendant
, nor does it apply to officers having custody of persons brought before the magistrate. Either party may challenge the exclusion of any person under this section. Upon motion of either party, the magistrate shall hold a hearing, on the record, to determine if the person sought to be excluded is, in fact, a person excludable under this section.

US Supreme Court, Daubert v. Merrell Dow Pharmaceutical 509 U.S. 579 113 S.Ct. 2786 (1993), effectively made the standard in federal court, as well as many other courts, as Rule 702 of the Federal Rules of Evidence:
"If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if (1) the testimony is based upon sufficient facts or data, (2) the testimony is theproduct of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case." (Amended effective December 1, 2000)

Chris Conrad, Cannabis cultivation, yields, dosages, collectives, dispensaries, illegal sales, and most things cannabis. Qualified as expert in 35 California counties, several other states, Federal, and Courts Martial. Mentioned favorably in California Supreme Court and Appeals Court rulings. Author of Cannabis Yields and Dosage.

Paul Armentano, Expert witness on drug testing

William Britt 562-818-0420, Expert on medical marijuana issues, Los Angeles, Southern California

Jason Browne 707-974-8264, Expert withess on medical marijuana issues, Northern California

Don Duncan, Expert witness on medical marijuana dispensaries

Dale Gieringer, Expert witness on drug testing

Brian Sedgwick Specializing in detection and toxicology

Dr. James Woodford

Specializing in smell and detection. News article mentioning Woodford: Send an email.

Zehnder, Jeffrey "drug detection laboratories" 916-366-3113

Raymond Grimsbo, PhD

President / Director, Intermountain Forensic Laboratories, Inc.
11715 NE Glisan St., Portland, Oregon 97220 / (503)257-7177, fax (503)257-8352

  • Forensic Scientist specializing in smell and detection. Email.
  • Video Depositions
  • California, based in the San Francisco Bay area
  • Raymond A. Grimsbo, Ph.D., D-ABC, FAAFS

If you wish to research the law without the assistance of a private attorney, you can visit the Internet web site where you can research California's laws online.

You may wish to consult the law librarian at your nearest law library. For the location of your county law library, please refer to your local telephone directory section on County Government Offices under "Law Library."

Attorney and Physician Referrals

From Safe Access Now, basically for medical marijuana or marijuana cases in the state of California.


Lots of good links, referrals and information

National Attorneys

This has a database of attorneys, you can read their resumes online.

California citizens, as well as out-of State citizens, may contact the Legal Services Department of the State Bar of California for referral to a local lawyer referral service at 415-561-8398.

Other resources for expert witnesses:

List of expert witness links Address: 122-A E. Foothill Blvd., PMB 123, Arcadia, CA 91006. Email:

Safe Access Now: Guidelines for Medical Marijuana dosages and cultivation

Other cannabis information sites