Thou shalt not bear false witness against thy neighbor. Exodus 20:16
Okay, we now come to the only commandment that I actually think is good. I actually have nothing bad to say about it. Though interestingly the reason I have nothing bad to say about it is because the command doesn't actually seem to be saying what most Christians assert that it says.
Almost without fail, Christians will tell you that this is a command to never lie. I would argue the wording is much more specific. In the context, the rule seems to be much more specific. To "bear false witness" seems indicate a legal meaning, meaning that the command is telling people to not accuse others of illegal activities they are not guilty of. In essence this command is one against perjury.
As such I find this command like the others, reasonable, clear, concise, and fairly closely matches laws in our own legal system. Of course it doesn't provide for what the punishment will be, but otherwise I have nothing really bad to say about this commandment. I just wish Christians would read it more closely and realize that this commandment does not deal with lying in general. Don't get me wrong I prefer honesty, but I don't think it makes sense to make lying a crime.