Unaccountable power, it turns out, can be rather useful—as long as you're the one who wields it.

That seems to be the lesson certain members of the Chicago City Council are learning as they ease into their new roles as representatives of wards that elected democratic socialists to represent them at City Hall.

Like the old Machine predecessors against whom they most likely would have railed—think Ald. Ed Burke, 14th—freshly minted progressive aldermen are discovering that unfettered aldermanic prerogative has its practical upsides. This tradition, cherished by self-dealing Chicago pols for decades, means the alderman has ultimate say-so over just about everything that goes on in his or her ward, and that the priorities of those who wish to do anything that requires city permits in a particular alderman's domain must align with those of the alderman if they have any hope of getting a go-ahead.

Two freshman aldermen in particular have realized the utility of this uniquely Chicago-style tradition. As Crain's Alby Gallun reported in the Dec. 6 issue, Ald. Byron Sigcho-Lopez, 25th, is using his newfound powers to hold up a New York real estate developer's plan for a 434-unit apartment project in Pilsen. And over in Humboldt Park, Ald. Daniel La Spata, 1st, balked at a New Jersey-based developer's proposal to convert a former elementary school into 116 apartments that would be marketed to public school teachers.

In both cases, the aldermen put the screws to the developers to designate a greater percentage of their units as affordable housing—though each proposal exceeded what current zoning laws require in affordable-housing set-asides.

Mayor Lori Lightfoot's administration has rightly identified affordable housing as a priority. She has also correctly identified aldermanic prerogative as a toxin infecting Chicago's body politic. Fixing both problems simultaneously will be especially difficult now that progressive aldermen—not necessarily her most natural political allies—have discovered how to flex their muscles to get what they want out of people who seek to invest in their wards.

But the mayor must pursue both priorities with equal fervor. A thoughtful, well-researched policy to promote affordable housing—not a checkerboard of various aldermanic fiats—is an absolute necessity, as Crain's Forum series recently spelled out in striking detail. Tackling the city's housing affordability problem requires a meaningful partnership with real estate developers willing to risk their capital to bring high-quality developments to Chicago's most investment-starved neighborhoods. Residents can and should have a say in what types of projects come to their neighborhoods. That, by the way, is what the Plan Commission is for.

But achieving the city's broader affordable housing goals gets harder if every deal is subject to a stickup, even of the ideological kind, from the local alderman.