§ 156.50 Offenses involving computers; defenses.
  In any prosecution:
  1.  under  section  156.05  or  156.10  of this article, it shall be a
defense that the defendant had reasonable grounds to believe that he had
authorization to use the computer;
  2.  under  section 156.20, 156.25, 156.26 or 156.27 of this article it
shall be a defense that the defendant had reasonable grounds to  believe
that  he  had  the  right to alter in any manner or destroy the computer
data or the computer program;
  3. under section 156.30 of this article it shall be a defense that the
defendant had reasonable grounds to believe that he  had  the  right  to
copy,  reproduce  or  duplicate  in  any manner the computer data or the
computer program.
.

(For verification consult Official Text at Senate Gopher site.)