Section IX-24: Rights of action not affected - Questioning action of Commission.

  The right of any person, firm, corporation, receiver or trustee
to institute and prosecute in the ordinary courts of justice, any
action, suit or motion against any public utility, or public
service corporation, or any individual, person, firm,
corporation, receiver or trustee, engaged in the public utility
business, shall not be extinguished or impaired by reason of any
fine or other penalty which the Corporation Commission may impose
or be authorized to impose upon such public utility, public
service corporation, or any individual, person, firm,
corporation, receiver or trustee engaged in the public utility
business, because of its breach of any public duty or because of
its failure to comply with any order or requirement of the
Corporation Commission; but in no such proceeding by any person,
firm, corporation, receiver or trustee, against such public
utility, public service corporation, or any individual, person,
firm, corporation, receiver or trustee engaged in the public
utility business, nor in any collateral proceeding, shall the
reasonableness, justness, or validity of any rate, charge,
service, practice, rule, regulation or requirement, theretofore
prescribed by the Corporation Commission, within the scope of its
authority, and then in force, be questioned.