Section 20-474.3. Failure to produce license; presumptive evidence of unlicensed activity

a. In any civil or criminal action  or  proceeding,  failure  by  a general vendor who is required to be licensed pursuant to
  the provisions of this subchapter  to  exhibit  upon  demand  a  general
  vendor's license in accordance with the provisions of this subchapter to
  any  police  officer or authorized officer or employee of the department
  or other city agency shall be presumptive  evidence  that  such  general
  vendor is not duly licensed.
    b.  In  any  civil  or  criminal  action or proceeding, failure by any
  person who is required to obtain a distributor's license pursuant to the
  provisions of this subchapter, or failure by the driver of such  person,
  to  exhibit  upon  demand a distributor's license in accordance with the
  provisions of this  subchapter  to  any  police  officer  or  authorized
  officer  or  employee  of  the  department or other city agency shall be
  presumptive evidence that such person is not duly licensed.