Fact Witness v. Expert Witness

Personal injury and domestic cases both have a common issue with regard to treating doctors and expert witnesses.  In both cases, many times doctors will treat a someone for an injury (mental or physical).  The issue then arises is this person an expert witness or merely a fact witness?  This is an extremely fact intensive area.  This is important as expert witnesses require extremely detailed disclosures under Rule 26 of the Mississippi Rules of Civil Procedure and under both the Uniform Circuit and Chancery Court Rules.  The best advice I have been able to get in this area is that if the doctor is going to testify to anything beyond simply what they did, an expert disclosure needs to be done.  Many times treatment requires a differential diagnosis along with analysis of the situation which gets into expert testimony.  I have had the court order the opposing parties' witnesses struck under this scenario in the past.