yamitami said:
Here is the thing: if the law is in the books then the cops have to follow it. It would be unethical for a cop to not follow the law even if they consider the law unfair. The people you need to be talking to/about is the lawmakers, not the people who enforce it.
This is an example of the correct definition of the ethical. (It is not completely relative as some of you think, you're confusing it with morality - different things.)
The police officer signs on to the force with an understanding that this means he is responsible for upholding the law, as written. If a law allows for officer discretion, as may have been there case in this scenario, it doesn't necessarily matter (ethically) what choice the officer made so long as it was in line with the law, and he followed through/took responsibility for that choice. If it is the case that the officer broke the law somehow, then it would be unethical. Even the choice to follow that person when he could have done other things is simply a choice in which he is allowed personal discretion - the system affords him that freedom to choose, so he is not in conflict with it.
Was it immoral? Depends on who you ask. There really isn't a single set morality these days to judge by, and the law is the closest tool we have to reflect democratic morality (even though it may not serve that purpose in all cases). So, you can think what the cop did was immoral in a broader perspective, but that doesn't mean it was unethical necessarily.