The housing crunch is creating pressure for the expansion of affordable housing in metros across the US. But in many places where new low-income units have been proposed, individuals and institutions are invoking obscure laws—some dating back nearly a century—to raise the bar for approval by local officials.

Last year, a non-profit organization applied for a rezoning of the shuttered Crowne Plaza hotel in Tulsa, OK. The group, Veteran Services USA, planned to renovate the 11-story building, operating floors two through six as a hotel and converting the top four floors into low-income rental apartments for veterans.

The veterans' organization in Tulsa had the support of the local planning commission, which voted six to four in favor of approving the project. Institutional neighbors of the hotel, including Oral Roberts University and Walmart, were able to block the plan by filing petitions that under state law triggered a requirement that the approval needed the support of a three-quarters supermajority of commission.