It would stop convicted murderers who refuse to disclose the location of their victim's body from becoming eligible for parole.
The Free Speech Union's letter said it was concerned about the repeated passing of laws under urgency.
But Tolkien's world-famous work is still covered by copyright in other countries.
It ruled that an ex-polyamorous relationship could all be entitled to a share of their former $2 million property.
The law update is still expected to be introduced as a bill to Parliament in the middle of the year.
Here are 12 pieces of legislation that are becoming law but haven't had much attention with everything else going on.
But other lawyers warn against reading too much into it.
The legislation passed with support from Labour and the Greens.
