OLYMPIA, Wash. — Importing items like elephant ivory or rhino horns into the United States for commercial purposes has been prohibited for decades under federal law and international treaties. In Washington, voters will weigh in on a ballot measure that would add state penalties to violators and expand the number of animals prohibited for trade.

The measure on November’s ballot would ban the purchase, sale and distribution of parts or products made from 10 endangered animals: lions, elephants, rhinos, tigers, leopards, cheetahs, marine turtles, pangolins, sharks and rays. Offenders could face a maximum penalty of five years in prison and a $10,000 fine.

Initiative 1401 is backed by billionaire Paul Allen and supported by the Humane Society of the United States and conservation and zoological groups. It is the first statewide vote on wildlife trafficking, though states like California, New York and New Jersey have enacted less sweeping legislation. Supporters of the issue in Oregon announced Monday that they are planning a measure similar to Washington state’s to appear on the November 2016 ballot.

Critics argue such measures will do little to help reduce poaching if other countries and states continue allowing sales of ivory products. But supporters argue that Washington can serve as a model for other states.