Hawaii Revised Statutes
702. General Principles of Penal Liability
702-219 Ignorance or mistake; reduction in grade and class of the offense. §702-219 Commentary:

§702-219 Ignorance or mistake; reduction in grade and class of the offense. Although ignorance or mistake would otherwise afford a defense to the offense charged, the defense is not available if the defendant would be guilty of another offense had the situation been as the defendant supposed. In such case, however, the ignorance or mistake of the defendant shall reduce the grade and class of the offense of which the defendant may be convicted to those of the offense of which the defendant would be guilty had the situation been as the defendant supposed. [L 1972, c 9, pt of §1; gen ch 1993]
COMMENTARY ON §702-219
This section is addressed to a limited problem. A defendant intending to commit a certain offense, may, because of reasonable ignorance or mistake on the defendant's part, engage in conduct which (if the requisite state of mind were present) would be sufficient for conviction of a graver offense. It would not be fair to convict the defendant of the graver offense (unless some reduction in penalty were made to reflect the defendant's actual culpability) and it would not be fair to allow a complete acquittal because the defendant intended some other offense than the one with which the defendant is charged.
The problem may be stated by borrowing an example from the Model Penal Code commentary:
Burglary of a dwelling house may, for example, reasonably be treated as an offense of greater gravity than burglary of a store; and it is not unreasonable to require knowledge that the structure is a dwelling or at least recklessness that such may be the case. If we conceive of a defendant who had every ground to think that it was a store, although it actually was a dwelling, it may not be right to hold him for the graver crime. The doctrine that when one intends a lesser crime he may be convicted of a graver offense committed inadvertently leads to anomalous results if it is generally applied in the penal law....
If the defendant in the circumstances supposed is exculpated of the graver crime, it seems clear, however, that he should not be acquitted.1
The Code, following the suggestion of the Model Penal Code, resolves the dilemma by authorizing conviction for the graver offense while limiting the sentence (the grade and class) to that authorized for the offense which the defendant would have committed had the situation been as the defendant supposed. This limitation reflects the defendant's limited culpability.
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§702-219 Commentary:
1. M.P.C., Tentative Draft No. 4, comments at 137 (1955).

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