Source : Free On-Line Dictionary of Computing

paranoid programming
     
         A programming style that tries to prepare for
        the worst external conditions, including incorrect input,
        resource limitations, hardware and software failure and even
        {can't happen} errors, to the fullest possible extent.  While
        some believe in the motto "professional programming is
        paranoid programming", the expression usually has the
        connotation that the efforts are unnecessary or too costly
        ("Maybe this code is just paranoid programming, but I think it
        is necessary to avoid a possible overflow condition".)
     
        (2001-01-27)