This is the kind of thing which makes one feel proud to be living in a democracy. The only opposition comes from big industry, which is doing its usual whining over having to accurately label its products.
There is a growing trend across the country to add this requirement to state laws. Vermont just this year became the first state to have such a law in effect, and Maine and Connecticut have enacted laws which have not yet taken effect.
Conservatives like to talk about how, in our federalist system, the states are supposed to be laboratories in which new ideas can be tried out to see how they work. The idea is that if a new idea works out on the state level, then perhaps it can be implemented on a national basis.
Well, the GMO issue is an example of states fulfilling this experimental laboratory role. The national Food and Drug Administration has declined to issue such a labeling requirement, even though a petition asking it to do so received more signatures than any petition in the agency's history. However, individual states like Oregon do not have to wait for the feds, and this measure will likely be passed overwhelmingly.
The measure would not take effect until 2016, giving industry more than a year to comply. This should give industry plenty of time to get up to speed on the law's requirements.