In an opinion last week, Judge Caproni ruled unlawful a memorandum issued by the Department of Interior that interpreted a provision of the Migratory Bird Treaty Act (“MBTA”) that prohibits killing “by any means whatever . . . at any time or in any manner, any migratory bird” to exclude incidental, unintentional killing.

The opinion begins:

It is not only a sin to kill a mockingbird, it is also a crime. That has been the letter of the law for the past century. But if the Department of the Interior has its way, many mockingbirds and other migratory birds that delight people and support ecosystems throughout the country will be killed without legal consequence.

Ultimately, Judge Caproni found that carving out unintentional killing could not be squared with the broad prohibition against killing “in any manner”:

Interior does not explain why the fact that the verb “kill” is associated with activity means that the phrase “by any means or in any manner” should be rewritten to state “by any means or in any manner of activity that is specifically directed at birds.” Killing a bird by firing a gun, setting a trap, dumping oil waste, or pressure washing nests from a bridge all fit within Interior’s active sense of “kill,” and yet [Interior] concludes that the first two are prohibited by the MBTA while the latter two are not.

Where, then, does Interior find its “directed at” limitation on the MBTA’s scope? First, Interior argues that when “kill” is read according to its surrounding words (known as the noscitur a sociis canon), the term adopts a narrower meaning. According to Interior, because “pursue,” “hunt,” and “capture” reference activities directed at birds, “kill” must also. But that use of noscitur is improper; it restricts the meaning of “kill” to “one of its many possible applications.” “Kill” is broad but not at all ambiguous. To kill a bird in the ordinary sense can be accidental; the action that kills does not have to be directed at birds in the same sense as hunting birds.