## Facts

- Bruce L. Johnson was charged with murder, kidnapping, and assault with intent to commit rape involving a 14-year-old girl.
- Johnson pleaded not guilty by reason of insanity.
- At trial, the jury rejected the insanity defense and found Johnson criminally responsible under Rhode Island’s then-existing M’Naghten-based insanity instruction.
- Johnson was convicted on all charges.

## Issues

1. Whether Rhode Island should abandon the M’Naghten rule and adopt the Model Penal Code “substantial capacity” test for criminal insanity.
2. If a new insanity standard were adopted, whether Johnson was entitled to reversal and a new trial under the new test.

## Decision

- The Rhode Island Supreme Court abandoned the M’Naghten rule as the controlling test for insanity.
- The court adopted the Model Penal Code standard: a defendant is not criminally responsible if, because of mental disease or defect, the defendant lacked substantial capacity either to appreciate the criminality (wrongfulness) of the conduct or to conform the conduct to the law.
- The court reversed Johnson’s convictions and remanded for a new trial applying the newly adopted standard.

## Legal Principles

- Criminal responsibility presupposes culpability; punishment is generally unjustified where mental illness sufficiently impairs the defendant’s capacity for blameworthy choice.
- The M’Naghten rule is inadequate where it confines insanity largely to cognitive incapacity and fails to account for significant volitional impairment.
- The MPC “substantial capacity” test addresses both cognitive and volitional impairment and does not require total incapacity.
- Even under the MPC standard, the jury remains the final decision-maker on criminal responsibility; expert testimony informs but does not decide the ultimate legal question.
- When a conviction rests on an insanity standard later rejected as legally insufficient, a new trial may be required so the defendant can present the defense under the correct standard.

## Conclusion

Rhode Island replaced the M’Naghten insanity test with the Model Penal Code’s substantial-capacity standard and ordered a new trial because the jury had evaluated Johnson’s criminal responsibility under an outdated and overly restrictive rule.


State v. Johnson, 121 R.I. 254, 399 A.2d 469 (R.I. 1979)