Recently, I recieved a notice on my door stating my trash bag was found beside the dumpster and I was being charged a $100 fine for the violation. I read the lease and it states that the first offense will be a written warning and the second will be a $100 fine. I called the property manager to dispute the fine since it was my first offense. She stated that there was a notice posted to the dumpster and that was the written warning. This notice was not there when the trash was left, but that is her word against mine. My question is, does the piece of paper taped to the dumpster count as the first warning?

No. And how do they know it's yours? How do they know you are responsible? How do they know someone didn't pull it out and put it there (yes that can happen, I did that once or twice when I was a kid).

Too many unanswered questions.

Well, this sounds like selective interpretation. If there is a process, contest the fine. They may ask you to leave and terminate the lease, or take legal action. You can then argue that there was no sign on the dumpster that was clearly visible to tenants and even if there was, it would not count as a first warning to you because it would have been something for the public at large, and your lease terms mandate that you specifically receive a warning, which you did not, just a fine. Another strategy is to talk to a higher up from the manager and explain that you do not think this is something where you all should have to go to court, but there was no warning given to you and there was no warning sign, so can they just give you a warning letter and be done wiht this.

I am very happy to report that the judge dismissed thier case against me. He said that a letter taped to a dumpster does not constitute proper written notification.

Now if I can get my whole security deposit back from them when I move out at the end of the month - I'll be doing good!