(a)      Except as provided in subsection (b) of this section, it is unlawful for a county commissioner, during his term of office, to accept, hold, purchase or acquire any claim on or against the county of which he is a commissioner, or any share or interest in such claim, if the claim has been or is to be passed upon and approved by the board of county commissioners of which he is a member.

      (b)      The provisions in subsection (a) do not apply in any county that has adopted local ethics laws under §§ 15-804 and 15-805 of the State Government Article, if such laws have been approved by the State Ethics Commission.