You can certainly dispute the charge. If you have no witnesses, then the court will have only your testimony and the officer's testimony to consider. The court may believe the officer over you.
On the other hand, if you have a clean record, you can plead nolo contendere (no contest) to avoid any points on your license.
An attorney familiar with the court might be able to work out some other disposition of the case to avoid a conviction or points.
He doesn't have to turn his blue lights on to stop you. I always recommend going to court. The prosecutor may reduce the charge so it does not go on your record. If your case is in Atlanta they will probably offer you the option of paying $150 in exchange for them dismissing your ticket.
James L. Yeargan, Jr. is licensed to practice law in the State of Georgia. All information given is based only on Georgia law, and is not directly applicable to any other jurisdictions, states, or districts. This response, or any response, is not legal advice. This response, or any response, does not create an attorney/client relationship. The response is in the form of legal education and is intended to provide general information. Any state specific concerns should be directed to an attorney who is licensed to practice law in that respective state.