This is part one of a two-part series. Part two will be available Friday.In a class action attacking the validity of the $50 filing fee a 2010 law imposed on residential mortgage foreclosure cases — to fund “housing counseling” and rehabilitate abandoned dwellings (including cutting grass, trimming trees, picking up trash and paying for repairs) — the named plaintiffs argued the “fee” was so disconnected from a legitimate legislative purpose that it violated their right, under Sec. 12 of …