In a classical Greek drama, when the hero is in grave straits, an immortal comes to save the day. The God is lowered to the stage from above by a machine — hence the term “deus ex machina”(God from the machine). While trial lawyers today do not have the deus ex machina, we have the next best thing — the expert witness, who can save the day not by force of arms but by rendering a lethal opinion.
The importance of the expert requires thorough appreciation of the rules governing expert testimony and keeping abreast of rule changes.