Today I got a ticket for not paying a ticket fare for the light rail. But the thing is I pre bought my tickets before so all I have to do is stamp them. Apparently one of my old tickets got mixed up with my new ones and I accidentally stamped the old ticket. I told the security guy it was an accident. Now I have to...
Being a first-timer with a plausible story is a good start. Unused tickets bought before the incident, or a receipt or bank statement showing you paid the rail service enough for several tickets will help.
Just go to court and be done with it. There will be a fine - one way or another you are guilty, even if it was a mistake on your part. You don't mention where on Earth you are but in the US (and I expect in the UK, where our system of laws has its roots) you will just plead guilty. No need to explain and I doubt it would make any difference. You will feel better afterward that it is over and the fine will not be crushing. You will be a bit stronger for the experience.
Get a lawyer.
Present the new ticket with proof you bought it before the ride where you got the problem with mixing them up.
If necessary, go to court. State the facts and respect the findings of the court.
The trouble is a lot of dishonest people do on purpose what you did accidentally. How can the rail network or the court tell who made an honest mistake and who is a fare cheat? Take legal advice/representation if you can afford it.
You may find you receive correspondence before any court case giving you an opportunity to state your defence in writing. On the strength of whatever you say, it is possible the matter could be dropped.
tell the Judge the same story .. you should get away with it .. don't worry they do not lock you up for things like this