The bar has been raised in order to qualify 'expert witnesses.' Rule 702 of the Federal Rules of Evidence** addresses the qualification of expert witnesses, as do procedural rules at the state level. This document by Roy Phillips and Thomas Veitch gives you the details.

INFORMATION DATE 19920827 DESCRIPTION USDOL Program Highlights-Responding to Workplace Emergencies TOPIC Worker Protection SUBJECT Protecting Workers in Imminent Danger ABSTRACT If a health or saf...