Beyond Reasonable Doubt

首先，你不能提前contest，應該按時間去回應。

其次，第一次出庭僅僅是plea guilty還是not guilty，如果你plea not guilty, 具體庭審要等再次安排。所以五月份那次去，你也沒有機會辯解。第一次出庭警察不會去，要等到庭審的時候警察才會出麵作證。

至於你的問題，你的根據是那個路口，沒有限時左拐的標誌，隻有限時右拐的標誌。而警察抓你的理由，“cannot turn into this street". 是假設左拐右拐都有限時。如果你證據確鑿，你可以試一試。可能那天標誌掉了，不是沒有可能。

關鍵詞是“beyond reasonable doubt”。  The police did not prove beyond reasonable doubt that I violated traffic control device.  My pictures show that there was no traffic control device prohibiting left turn at the crossroad. 

CA Vehicle Code 

22101.  (a) The Department of Transportation or local authorities in
respect to highways under their respective jurisdictions, may cause
official traffic control devices to be placed or erected within or
adjacent to intersections to regulate or prohibit turning movements
at such intersections.
   (b) When turning movements are required at an intersection notice
of such requirement shall be given by erection of a sign, unless an
additional clearly marked traffic lane is provided for the approach
to the turning movement, in which event notice as applicable to such
additional traffic lane shall be given by any official traffic
control device.
   (c) When right- or left-hand turns are prohibited at an
intersection notice of such prohibition shall be given by erection of
a sign.
   (d) When official traffic control devices are placed as required
in subdivisions (b) or (c), it shall be unlawful for any driver of a
vehicle to disobey the directions of such official traffic control
devices.