It's hard to argue your case without a solid evidence or a witness. The judge will more likely trust the officer.
About the ticket, if you decide going to court, you will have about 30 seconds to talk to the judge.
Basically, he'll call your name, then read the document which something like this: On xx day, it is said that you were running the red light, do you plead guity, not guity or no contest?
1. If you admit that you're guilty, you'll pay the fine, which can be bargain with the judge, something like you're student, dont have money, etc. He can reduce the price, and even let you make monthly payment. In CA, fine is $300 for running red line, stop sign, turning right on red without making a complete stop (I got ticket at stop sign once). This will remain on your driving record for 3 years
2. If you say that you're not guilty, he'll set you another court date at a difference court room in which you'll be there with the officer to express your situation. The judge will listen to both of you and make a decision. But most of the time you'll lose.
3. No contest. You don't admit nor deny that you made a mistake. However, you'll pay the fine same as you plead guilty.
4. "Traffic school, your Honor!" This is what your gf should tell the judge if she didn't go to the traffice school in the last 18 months.
Just right after she hears "guity, not guity or no contest?" from the judge, she should just say "Traffic school, your Honor!". Don't need to say anything else since the judge doesnt have much time. He must go through about 60 people within 2 hours.
She then has to pay the fine (can't bargain the price in this case, $300 firm), then she goes to the office next door to register for a class which will cost about $30 (or that what I paid) in addition to $300 fine and choose a date, either 2 evening nights of 4 hours or one 8 hours class on Saturday. She must be there on time and remain in the class until the end when she'll be given the certificate of completion. Why would she go for all that trouble? Because it won't show in her record if she completes the "driver education course".
My friend had got a ticket at stop sign and he was unable to attend and reschedule the class, his insurance premium has increased $100/yr (from $700 to $800)
Good luck to you!