LawGuru.com poses the question “What constitutes an”expert witness”? Attorney Jonathon Moseley answers:
This is an interesting question, and this is one of the biggest reasons why “pro se” plaintiffs (without an attorney ) often lose in court. A “fact witness” is someone who simply testifies to what they saw, or heard, or know. “The light was red, when the car went flying through.” That is simply a fact. ANYTHING which requires some opinion or analysis or conclusion, however, requires an “expert witness.” For example, “If the brakes were in good condition, the driver should have been able to stop in time and avoid the accident.” Says who? That is not a fact that can be observed and testified about. That is an opinion (says the law). Actually it is an engineering and scientific conclusion based upon the laws of physics and the characteristics of cars. However, it takes an “expert” to testify to that, or you cannot introduce any such evidence into the trial.
Or: “It will cost $5000 to repaint the house because the contractor botched the job.” Says who? The court will not allow such testimony, to establish the cost of repainting, unless you have an “expert witness” to express his educated OPINION as to how much money it will cost to repaint (how much time, how big the house is, whether painting certain areas are easy or hard, etc.)
An expert can be an expert without any training, because of simple experience. Someone who dropped out of high school but spent 8 years painting houses can testify as an expert on the cost of repainting a house after a contractor damaged it or botched the paint job. A high school dropout who repairs pianos can testify to the cost of repairing a piano after the moving company DROPPED it while moving it.