Stopped yesterday and told that I was going 55 mph in a 40mph zone.  I
had no clue why I was stopped and the sign right in front of me said
55mph.  Went back today and the sign before the speed trap was
obscured by leaves and a tree branch.  Also, the lines for the
stopwatch zone were on a curve -- wouldn't this change the results?
How best can a defend myself in front of a District Magistrate???

A picture is worth a thousand words.  Maybe you could take a few
pictures of the obscured sign at the same time of day with similar
weather, noting the distance for each picture.  Good luck.