Milton’s case against MBTA law heads to SJC

Yes, the train is orange. But this is a stop on the Red Line in Milton.Lane Turner/Globe Staff

Same-sex marriage. Gun rights. Murder convictions. The Massachusetts Supreme Judicial Court deals with plenty of big, serious issues.

Next week, it’ll be asked to decide whether the Mattapan trolley is, or is not, a subway.

The town of Milton has challenged the state’s controversial MBTA housing law — which requires municipalities served by the T to set aside land for denser housing development — in a closely watched case that has critical implications for the state’s housing crisis.

The case itself is a big deal, no doubt. But it could hinge on a semantic dispute about the quirky, 2.6-mile Mattapan trolley, which runs from the Red Line station in Ashmont to Mattapan Square, passing through the northern part of Milton.

The state considers the line to be part of the Red Line and thus part of the core rapid transit system, a determination that meant Milton was subject to higher requirements under the law. Milton disagrees.

There are several other issues at stake in the litigation, including the extent of Attorney General Andrea Campbell’s powers to enforce the MBTA law, meaning the court won’t necessarily have to reach any conclusions on the trolley question.

But if it does, the litigants, and the large number of interested parties that filed amicus briefs in the case, had plenty to say.

The dispute is important because the law imposes the highest requirements on municipalities that have “subway stations.” But the trolley is not a subway, Milton argues, citing three different dictionaries that all describe subways as going underground. (“Dictionaries are useful aids in determining a word’s ordinary meaning,” the town’s brief says with a hint of snark.) Not being a subway, it therefore cannot have “subway stations.” Even if the word subway is construed to include above-ground portions of a line that is partially underground, Milton points out the trolley isn’t physically connected to the rest of the Red Line and that passengers have to transfer at Ashmont.

A trolley on the Mattapan Ashmont High-Speed trolley line leaves Ashmont Station in Dorchester. The trolley through Milton to Mattapan Square extends the Red Line, which would otherwise end at Ashmont, the terminal for heavier subway trains.Lane Turner/Globe Staff

The attorney general’s brief says that subway stations were reasonably defined as “any of the stops along the MBTA Red Line, Green Line, Orange Line, or Blue Line” and that the Mattapan line was reasonably considered part of the Red Line. It makes the most sense, the AG argues, to interpret “subway” as referring to the type of system of which the Mattapan Line is a portion. After all, if the Mattpan Line isn’t part of the subway system, then what is it part of?

The AG points out that if the court rules the Mattapan Line is not a subway for the purposes of the MBTA law, it would raise questions about how to apply the law to communities that have only above-ground service on the Red, Orange, Blue, and Green lines.

It’s unfortunate that the Legislature left any ambiguity when it drafted the law — but it did, and here we are.  As this newsletter has covered before, the Mattapan Line has more than its share of historical peculiarities — and now it could add to that history a cameo role in a critically important court case.

This is an excerpt from Are we there yet?, a Globe Opinion newsletter about the future of transportation in the region. Sign up to get it in your inbox early.