In § 6-5-548(a), Ala. Code 1975, the Legislature specifically provided that in medical-liability cases "the plaintiff shall have the burden of proving the defendant's liability by substantial evidence." In § 6-5-549, the Legislature provided:
"In the case of a jury trial, the jury shall be instructed that in order to return a verdict against a health care provider, the jury shall be reasonably satisfied by substantial evidence that the health care provider failed to comply with the standard of care and that such failure probably caused the injury or death in question."
In Gradford, a case that did not arise under the provisions of the Alabama Medical Liability Act, §§ 6-5-480, Ala. Code 1975, et seq., this Court held:
"Clearly, the substantial evidence rule pertains only to 'rulings by the court' on the sufficiency of the evidence as presented by motions for summary judgment or motions for judgment as a matter of law (the current terminology; see Rule 50, Ala. R. Civ. P.)." 699 So. 2d at 150. This Court also held:
"Just as it is not error not to charge on 'substantial evidence,' it is error to give a charge telling the jury that it must be 'reasonably satisfied by substantial evidence.'
"The giving of such a charge is error, both because the substantial evidence rule has no place in the jury's deliberations and because the charge has a tendency to mislead and confuse the jury. Although the circuit court here instructed the jury on the legal definition of 'substantial evidence,' the repeated use of that term may have confused the jury because of the ambiguity of the word 'substantial.'" 699 So. 2d at 151.