What is the name of your state (only U.S. law)? California
When one submits an appeal for a parking violation claim to be evaluated and subsequently approved or denied, who is actually doing the evaluation of the appeal? One representing the plaintive city claim, or an impartial individual with no ties to defendant or city plaintive? If this individual evaluating the appeal is an employee of the city making the claim, would that be a conflict of interest?
The "who" can vary, but, in general the initial appeal is before a hearing officer or panel appointed by the city to hear such appeals. The person may be contracted for these matters, or an employee. For my city, I hear these appeals.
If you lose, there should be a secondary appeal to a supervisor or board that can overrule the initial hearing officer or panel. In my city, the appeal would be to the Chief.
Finally, you can pay for a shot before a judge, but if you lose, it's an extra $50 or so (though, some say, $25).
How we work it in my city is that I hear the appeal and evaluate the matter for the law ... was the citation completed properly (within the law, for the correct section, and applicable), and did the registered owner have a lawful justification for his actions. That is not to say a REASONABLE one, only one that legally renders his requirement to park within the law moot.
If I rule against the owner, he or she can have a hearing with the Chief who is free to dismiss the matter for any reason he wishes (a good sob story, hardship, a reasonable action even if not lawful, etc.).
Finally, they can take the matter to court (rarely done).
At my level I rarely have to dismiss a parking cite, When I do dismiss it's usually because the officer failed to cite the proper section or the location or vehicle information is inadequate or incomplete.
As for a "conflict of interest," no. If the hearing officer or panel received some sort of remuneration as a result of sustaining the parking cite, maybe so. As it is, I get paid the same no matter how I decide. And, since parking cite revenues go into the General Fund, the police department receives no direct benefit (though, I suppose one could argue that since the PD receives most of its funding through General Fund allocations that it does benefit down the road). But, this has ever been ruled unlawful by any court, and you do have the right to have it heard by a judge later if you don't like the results.