Interesting topic, not sure on certain things as others have said. Blatant violations without a doubt will call in and will stop hunting or fishing with the individual. On other things I know people who have violated the law at least from what their story was but cant say I would turn them in. Give two examples.
One guy went fishing with his buddy, well in our state your only allowed 1 Red Drum per person well they kept two reds but only one guy caught the two the other guy kept catching junk fish. Technically he violated the law because you cannot catch your limit and then someone elses but alot of people on the water do it.
Have seen the same thing with duck hunters. One guy gets his limit but helps fill the other limits of those out with them instead of sitting it out.