In another loss for federal immigration officials, the highest court in Massachusetts decided yesterday that it is illegal under state law to hold someone on an immigration detainer. Lunn v. Commonwealth, No. SJC-12276, slip op. (Mass. July 24, 2017). This case involved a man who was held in a courthouse holding cell after the judge overseeing a criminal prosecution against him dismissed the case. [Disclosure: I was one of many immigration law scholars to sign a brief authored by my colleague Christopher Lasch submitted on behalf of Mr. Lunn.]

The state’s Supreme Judicial Court easily concluded that Lunn’s time in the courthouse cell constituted an arrest. Unlike investigatory stops authorized by Terry v. Ohio, Lunn’s confinement was not a brief restraint to give police officers time to gauge whether probable cause exists that he committed a crime.

On the contrary, Lunn’s arrest pursuant to the detainer was related to the federal government’s power to pursue removal against a person. Courts, including the United States Supreme Court, have routinely characterized the removal process as a civil proceeding; as a matter of law, it is not a criminal matter.

Like the rest of the United States, Massachusetts law presumes that the government can’t arrest people without reason. In Massachusetts, only the common law and state statutes identify permissible bases for arrest. Neither, the court concluded, explicitly references immigration detainers, thus neither can be said to authorize arrests for this reason. Things might have turned out differently had the state legislature enacted a statute authorizing compliance with detainer requests. At least then the court would have had to address thorny constitutional questions that it avoided.

The federal government, participating in the case as amicus curiae, urged the court to conclude that state law grants police officers “inherent” or “implicit” authority to arrest people solely because of a detainer. The court declined to do so. “Where neither our common law nor any of our statutes recognizes the power to arrest for Federal civil immigration offenses, we should be chary about reading our law’s silence as a basis for affirmatively recognizing a new power to arrest,” the unanimous court wrote.

Under President Obama, the use of immigration detainers peaked and plummeted. In 2011, for example, ICE issued almost 310,000 detainers. In 2015, however, it issued 95,000. So far under President Trump, ICE has been reluctant to disclose its detainer practices making accurate assessment difficult. There is every reason to believe that the Trump administration is making frequent use of detainers. Plus, state efforts to ratchet up the consequences of violating immigration law, including the controversial Senate Bill 4 in Texas, turn on compliance with detainers. As such, the legality of immigration detainers will likely remain an important matter for the foreseeable future.