Harris said in a written statement the law that was used to overturn the conviction of a man -- charged with having sex with a teenage girl in a darkened room while passing himself off as her boyfriend -- needs to be brought up to date.
A state appeals court said the 19th century law provided a loophole that allowed Julio Morales to carry out the charade in 2009. The court found the rape statute did not apply in the incident since the woman was not married at the time.
The conviction would have been upheld if the girl had been married and Morales had falsely told her he was her husband.
"This law is arcane and I will work with the legislature to fix it," Harris said. "The evidence is clear that this case involved a non-consensual assault that fits within the general understanding of what constitutes rape."
CNN said Morales testified at his trial in Los Angeles County he had told the alleged victim he was not her boyfriend.
As a result, the appellate court found the prosecution had incorrectly argued the points of the law.
"We conclude that under the peculiar facts of this case, reversal is required because the prosecutor argued an incorrect theory of guilt, the instruction permitted the jury to convict on that theory, and the record does not permit us to find that the jury relied only on the prosecutor's correct theory," the court said.