If you contest, you lose the opportunity to do traffic school.
As to fighting a moving vehicle violation you would be challenging the validity of the facts stated by the officer. If the officer’s notes lack key details you can challenge the officer’s memory. Key details would consist of the lane you were in (should be mentioned), weather and road conditions for justifying the officer’s citation of unsafe turn and location of officer whether they had visible view of the road conditions to make the appropriate call.
I am going to assume you were cited with VC 22107. Which provides that:
No person shall turn a vehicle from a direct course or move right or left upon a roadway until such movement can be made with reasonable safety and then only after the giving of an appropriate signal in the manner provided in this chapter in the event any other vehicle may be affected by the movement.
If this is what you were cited with you would need to focus on whether making the turn was safe, whether other vehicles could have been affected by the movement given the weather and road conditions that day.
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