In New York City, proximity to the subway is a decisive factor in real estate values. Lately, some urban reformers and liberal politicians have advocated taking some of that value back to fund the imperiled subway system itself, in the form of special taxes calculated specifically with this relationship in mind.

Value capture, as the policy idea is called, is “the solution of the moment” according to one business community leader quoted in the New York Times, and an “innovative financing mechanism” according to the president of an urban policy advocate group. Now, Governor Andrew Cuomo has gotten on board, making value capture a centerpiece of his subway system rescue plan.

It makes sense. Some private property owners benefit enormously from a publicly funded system, and it’s logical that they should pay a share of that additional, unearned revenue back into the system itself — especially because that system is in crisis. But value capture is also a complicated technocratic intervention, one that would require the creation of a new bureaucracy to evaluate the specific impact of transit lines on real estate prices over time, and entail a controversial and likely difficult effort to mediate between the transit authority and the city.