I found this that seems to add a little insight.
‘Sharia law’ measure sparks debate » Features » Tahlequah Daily Press
The sole reason for adding Sharia law was apparently a case in New Jersey.
"One case cited by both sides in the debate over Sharia law concerns a New Jersey rape incident. The people involved were Muslims from Morocco. The judge recognized that the defendant had engaged in sexual relations with the plantiff, over her objections, in November 2008 and again in January 2009. However, he did not find that sexual assault or criminal sexual conduct had occurred.
Judge Joseph Charles wrote in his opinion, “The court believes that he was operating under his belief that it is, as the husband, his desire to have sex when and whether he wanted to, was something that was consistent with his practices and it was something that was not prohibited. After acknowledging that this was a case in which religious custom clashed with the law, and that under the law, plaintiff had a right to refuse defendant’s advances, the judge found that defendant did not act with a criminal intent when he repeatedly insisted upon intercourse, despite plaintiff’s contrary wishes.”'
If it hasn't been done already, I think that Judge Joseph Charles needs to be removed. And I tend to agree that the law is likely a waste of paper. But it was passed by 70% of the voters. Being a waste of paper doesn't seem to be a valid reason to dismiss it.