Fighting a stop sign ticket can be an uphill battle when it just comes down to your word against that of the officer. Simply put, in most cases, the judge is going to believe the officer. But you still might have some good options for fighting your ticket without making it an issue of the officer's credibility.
Stop sign laws generally read something like this:
"The driver of any vehicle approaching a stop sign at the entrance to, or within, an intersection, shall stop at a limit line, if marked, otherwise before entering the crosswalk on the near side of the intersection. If there is no limit line or crosswalk, the driver shall stop at the entrance to the intersecting roadway or railroad grade crossing."
If you decide to take your case to trial, the government has to prove that you committed the violation. That means there generally must be proof of the following three elements (parts that make up the offense):
Basically, to get a conviction, the government needs to show you either didn't stop or stopped too late.
Most statutes say you must stop at the nearest of the limit line, crosswalk, or entrance to the intersection. Practically, this means you must stop slightly before you reach one of these points. Some conscientious drivers, however, stop well in advance of where they have to. In these cases, an officer hiding behind a bush 50 feet down a side street might not be able to see whether the driver stopped or not.
To mount this defense, you'll first want to request a copy of the officer's notes. Typically, this involves making a written request to the police department or local prosecutor's office through a process called "discovery." The notes, if obtained, can be used to verify where the officer was positioned when you allegedly ran the stop sign. In many cases, the officer won't have any notes, so you'll just have to ask the officer during cross-examination about where he or she was positioned when the violation allegedly occurred.
For this type of defense, it's also important to have a visual aid so you can show the judge the physical layout. In many situations, taking pictures of the scene will do the trick. Especially if you can document a visual obstruction—and convincingly testify you did stop—this defense can be a winner. Of course, it's a big help if you can produce a passenger or other witnesses who can corroborate your version of events.
Generally, you can't be prosecuted for running a stop sign that was obscured or illegible. With a defense based on obscured or illegible signage, you essentially concede that you ran the stop sign but argue it wasn't your fault because the sign wasn't visible. This can occur if the stop sign is hidden by storm-blown branches, twisted the wrong way by kids, or obscured in any other way.
Pictures are worth a thousand words. Pictures taken from different angles or distances are generally more convincing than just an explanation. For example, if a stop sign is hidden from view by overhanging branches until a few feet before the intersection, take pictures or a video from inside of your vehicle (with someone else driving) as the car approaches the sign. In court, you can show your pictures or video to the judge and explain the situation.
Ignorance is no excuse. It's not a valid defense to say you didn't know that what you did was illegal (rolling through a stop sign, for example). In other words, the law assumes that drivers know the rules of the road.
Generally, the fact that a sign was recently installed isn't a valid defense to running it. However, there's no question that it's easy to miss a new sign placed on a road that you travel regularly. So, some judges might be sympathetic and let you off the hook or at least reduce your fine if you can show the sign really was recently installed.
Crosswalks and limit lines fade. If you are ticketed at a stop sign for stopping a little too far into an intersection, you may be able to beat your ticket by showing that the limit line or crosswalk was too faded to see clearly. (Here again, a picture or video is probably necessary.) But it depends on the specific wording of your state's law. With the example above, this defense probably wouldn't work because the law requires drivers to stop at the nearest of a limit line or the intersection itself.