I found this:

http://en.wikipedia.org/wiki/California_Correctional_Peace_O...

So they lobby to increase prison terms and to "enforce current drug laws". I suppose they should have the right to do that, but it still seems a bit odd to me!

There are about 1/2 million correctional officers in the US:

http://www.bls.gov/ooh/protective-service/correctional-offic...

So they might be able to have quite some impact by lobbying and voting as a block, but they are not a big enough body to swing votes against a meaningful majority.

(your link states that union has ~31,000 members, California had about 17.5 million registered voters in the Nov 2014 election)

Yes, they do have a right to do that. NAMBLA also has that same right. I also have the right to call them both a cancer to society.

>enforce current drug laws

That reads to me like it could mean "outlaw medical marijuana."