But other doctors and critics of the lines challenge that comparison.

But critics challenge the figures and add that even if crime is down, the Mayor hasn't had much to do with it.

Some human rights advocates and political critics have challenged the view that the administration has changed its approach.

Critics challenged the program as a potential invasion of privacy.

But critics have challenged those estimates as too high.

Critics challenged aspects of the story which Haley claimed to be true.

Still, some conservative critics challenge the consensus, arguing that the money will be wasted.

Critics challenged the Justice Department's energetic defense of the law.

Critics challenged doctors to clarify what worked and, just as important, what did not.

Critics also challenge scientific evidence like ozone depletion and global warming.