Editing Expert witness (section)

== Types==

===Testifying experts===
If the witness needs to testify in court, the privilege is no longer protected. The expert witness's identity and nearly all documents used to prepare the testimony will become discoverable. Usually an experienced lawyer will advise the expert not to take notes on documents because all of the notes will be available to the other party.

An expert testifying in a United States federal court must satisfy the requirements of Fed. R. Evid. 702.<ref name="FRE702" /> Generally, under Rule 702, an expert is a person with "scientific, technical, or other specialized knowledge" who can "assist the trier of fact," which is typically a jury. A witness who is being offered as an expert must first establish his or her competency in the relevant field through an examination of his or her credentials. The opposing attorney is permitted to conduct a [[voir dire]] of the witness in order to challenge that witness' qualifications. If qualified by the court, then the expert may testify "in the form of an opinion or otherwise" so long as: "(1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case."

Although experts can testify in any case in which their expertise is relevant, criminal cases are more likely to use [[Forensic science|forensic scientists]] or [[Forensic psychology|forensic psychologists]], whereas civil cases, such as [[personal injury]], may use [[Forensic engineering#Forensic engineering|forensic engineers]], [[Accountant#Forensic accounting|forensic accountants]], [[employment consultant]]s or [[Health care|care]] experts. Senior [[physician]]s – UK, Ireland, and Commonwealth [[Consultant (medicine)|consultants]], U.S. [[attending physician]]s – are frequently used in both the civil and criminal courts.

The [[Federal Court of Australia]] has issued guidelines for experts appearing in Australian courts.<ref>Guidelines for Expert Witnesses in Proceedings in the Federal Court of Australia, Practice Direction, (Federal Court of Australia, 2007)</ref> This covers the format of the expert's written testimony as well as their behaviour in court. Similar procedures apply in non-court forums, such as the Australian [[Human Rights and Equal Opportunity Commission]].<ref>The accidental expert witness, Tom Worthington, Information Age (IDG, 2005)</ref>

==== Educating witness ====
The educating witness teaches the fact-finder (jury or, in a bench trial, judge) about the underlying scientific theory and instrument implementing theory. This witness is an expert witness, called to elicit opinions that a theory is valid and the instruments involved are reliable. The witness must be qualified as an expert witness, which may require academic qualifications or specific training.

==== Reporting witness ====
Called after teaching witness leaves stand. Usually the laboratory technician who personally conducted the test. Witness will describe both the test and the results. When describing test, will venture opinions that proper test procedures were used and that equipment was in good working order.<ref name="EvidenceNineties">{{cite book |last1=Carlson |first1=Ronald L. |last2=Imwinkelried |first2=Edward J. |last3=Kionka |first3=Edward J. |date=1991 |title=Evidence in the nineties: cases, materials, and problems for an age of science and statutes |publisher=Michie Co |isbn=978-0-87473-740-0 |url=https://books.google.com/books?id=HuFFAQAAIAAJ&q=laboratory+technician+reporting+witness+equipment}}</ref>

===Non-testifying experts===
In the U.S., a party may hire experts to help them evaluate a given case. For example, a car maker may hire an experienced mechanic to decide if its cars were built to specification. This kind of expert opinion will be protected from [[discovery (law)|discovery]] by the opposing party. In other words, if the expert finds evidence against their client, the opposite party will not automatically gain access to it. This privilege is similar to the [[work-product doctrine]] (not to be confused with [[attorney–client privilege]]).

The non-testifying expert can be present at the trial or hearing to aid the attorney in asking questions of other expert witnesses. Unlike a testifying expert, a non-testifying expert can be easily withdrawn from a case. It is also possible to change a non-testifying expert to a testifying expert before the expert disclosure date.<ref name="Eri">{{cite web|last=Eri J.D.|first=Christopher|title=What are the differences between an expert witness and a consultant non testifying expert|url=http://www.forensisgroup.com/resources-for-attorneys/what-are-the-differences-between-an-expert-witness-and-a-consultant-non-testifying-expert/|work=Forensis Group|date=19 November 2013|access-date=19 November 2013|archive-date=23 January 2014|archive-url=https://web.archive.org/web/20140123013215/http://www.forensisgroup.com/resources-for-attorneys/what-are-the-differences-between-an-expert-witness-and-a-consultant-non-testifying-expert|url-status=dead}}</ref>