The problem of delineating the boundaries of discovery under Rules 26-37 of the Federal Rules of Civil Procedure is constant, for the language of limitation in the rules themselves remains vague. The discretionary nature of these rules suggests determination of each case on its own record. The burden so imposed on district judges and the lack of definite standards in the rules themselves governing the exercise of discretion have undoubtedly contributed to the adoption by many judges of rather inflexible ancillary rules for the application of discovery in questionable areas. One of these areas concerns the extent to which expert witnesses' are subject to the discovery rules.
Jeremiah M. Long,
Discovery and Experts under the Federal Rules of Civil Procedureq,
39 Wash. L. Rev.
Available at: https://digitalcommons.law.uw.edu/wlr/vol39/iss4/3