Via Fred Clark:
Civil disobedience can be a powerful tool of nonviolent change, but it is really only appropriate or effective in response to an unjust legal prohibition. It does not apply easily or work well as a protest against what one regards as an unjust lack of legal prohibition.
Let’s consider an unlikely hypothetical situation. The governor’s ex-wife collected stamps, so the governor railroads through legislation banning stamp-collecting and imposing mandatory life sentences for all convicted philatelists. That would be an unjust prohibition, and thus civil disobedience would be an appropriate and powerful tool against it. The strategy is obvious — everyone collects stamps until the courts are swamped and the jails are filled or until the outcry forces the unjust law to be repealed.
But consider the opposite situation: The law permits stamp-collecting, but you feel it ought to be prohibited — you believe that the lack of a prohibition is itself unjust. You’re not without options in that situation — there are paths you can take and strategies you can pursue to try to get such a prohibition written into law. But civil disobedience will not help you. This particular context will not allow for the use of that particular tool.