## Facts

- Patients sued an orthopedic surgeon (Porretta) for medical malpractice; the jury returned a defense verdict.
- In that case, the trial court instructed that no physician is required to guarantee results, while also stating the applicable professional standard of care for orthopedic surgeons under like circumstances.
- In a consolidated malpractice case, a surgical patient developed brachial plexus palsy after an extended operation and sued the anesthesiology providers, relying on *res ipsa loquitur* (negligent positioning or monitoring inferred from the nature of the injury and defendants’ control during surgery).
- There, the trial court gave a “no guarantor of results” instruction and added that an adverse result after surgery is not, by itself, evidence of negligence; the jury returned a defense verdict.
- The intermediate appellate court treated “no guarantor” language as erroneous and applied a presumptive prejudice approach, reversing in the consolidated case and raising the same instruction issue in the orthopedic-surgeon case.

## Issues

1. Whether instructing a jury in a medical malpractice case that a physician is “not a guarantor of results” is erroneous.
2. Whether adding that “the mere fact that an adverse result may occur following surgery is not in itself evidence of negligence” improperly affects the jury’s consideration of negligence, including *res ipsa loquitur* theories.
3. Whether alleged instructional error requires reversal or must be assessed by examining the instructions as a whole for prejudice.

## Decision

- The Michigan Supreme Court held that “no guarantor of results” language is not categorically improper; propriety depends on the full instruction and trial context.
- The Court affirmed the defense verdict for the orthopedic surgeon because the instruction immediately and clearly paired the “no guarantor” statement with an affirmative, correct statement of the physician’s duty of care.
- The Court reversed the defense verdict for the anesthesiology providers and remanded for a new trial because the added “adverse result is not evidence of negligence” language, in context, was erroneous and prejudicial.
- The Court rejected a blanket presumption that any erroneous “no guarantor” instruction is automatically prejudicial; instead, courts must assess whether the charge, read as a whole, fairly presented the law and issues.

## Legal Principles

- In Michigan medical malpractice actions, a physician is held to the degree of skill, care, knowledge, and attention ordinarily possessed and exercised by practitioners in the same specialty under like circumstances.
- Jury instructions are evaluated in their entirety; the question is whether they fairly and adequately present the applicable law and the parties’ theories.
- “No guarantor of results” language may be permissible when it is balanced by a clear, correct, and affirmative statement of the standard of care, such that it does not mislead or dilute the duty owed.
- In cases where the plaintiff relies on inferential proof (including *res ipsa loquitur* supported by expert testimony), instructing that an adverse outcome is not itself evidence of negligence can improperly skew the jury’s evaluation by discounting permissible inferences from the event and surrounding circumstances.
- Appellate review of instructional error focuses on context-specific prejudice rather than categorical reversal rules.

## Conclusion

The Michigan Supreme Court treated “no guarantor of results” instructions as context-dependent: acceptable when paired with a correct standard-of-care instruction that preserves the defendant’s duty, but reversible error when expanded in a way that can interfere with legitimate inferences of negligence, particularly in *res ipsa loquitur* settings.


Jones v. Porretta, 405 N.W.2d 863 (Mich. 1987)