Just as an end-of-year lawsuit launched a broadside against a decades-old policy to boost affordable development, state lawmakers moved to make it easier for cities and towns to roll out their version of that same policy.

A Cambridge developer is arguing that the city’s so-called inclusionary zoning program, which requires developers to set aside a number of units for lower- and middle-income people, is unconstitutional at its core. The suit aims to crack the foundations of inclusionary zoning in Massachusetts, adopted by communities like Boston, Cambridge, and Somerville.

Meanwhile, senators struggling to make headway on a housing crunch across affordability levels are looking to pull all the levers they can, including lowering the difficulty of implementing inclusionary zoning locally.

The legal and legislative moves set up a clash over rules governing housing development at a time when there’s broad consensus that the state needs to build more units across communities.

Inclusionary zoning rules condition getting permits to build residential projects of a certain size on making a percentage of the units affordable. Cambridge credits its inclusionary zoning policy with creating over 1,600 units of affordable housing, and Somerville in 2023 described its policy as the “primary pipeline adding to the City’s permanent affordable housing stock.”

But a lawsuit filed last month in Land Court by Cambridge zoning attorney and developer Patrick Barrett and the conservative Pioneer Legal Foundation claims that the Cambridge policy is unconstitutionally forcing developers to “surrender fundamental property rights” by selling their units at lower than market rate.