The Supreme Judicial Court yesterday overturned a Tyngsboro man's conviction for "interference with a police officer," saying he had a First Amendment right to yell at the cops trying to confiscate his collection of 15 guns and that prosecutors failed to prove he physically tried to block them from taking away the weapons.

Sounds simple enough, but the state's highest court first had to determine whether "interference with a police officer" was even a crime, because it's not written down in a statute passed by the legislature but is instead something that has been passed down through the centuries as a chargeable offense. The ruling that the offense is, indeed, a common-law crime that dates back centuries, comes at a good time - as the number of people charged with "interference with a police officer" in Massachusetts has been increasing dramatically, from just one person in 1977 to 335 last year.

To establish that the charge reflects something that is legally a crime, the court had to examine judicial decisions dating back to an English case in 1634 involving a man whose answer to constable who wanted to know what the stranger was doing in the constable's town during a plague epidemic was deemed "scornfull."

After concluding that "interference with a police officer" was a common-law crime in England, which meant it became one in colonial Massachusetts, the court concluded that it became a law of the Commonwealth in 1780, when the state constitution was enacted with a provision that said any such unwritten laws would remain in effect unless overturned by either an act of the legislature or a court ruling, neither of which had ever happened here.

The court noted a series of post-Revolution rulings in Massachusetts that could not have happened had it not been a crime, including an 1845 case in Boston: A police officer named Grant Learned was performing the equivalent of a detail assignment when he arrested a guy in a theater for being drunk and disorderly. But while escorting the guy to jail, Learned softened and agreed to let him go after he said he would go straight home, only he didn't, he instead went straight into a bar, and Learned, realizing he'd been had, went in to re-arrest him and take him to jail for disobeying his implied order to go home - but this time had some trouble because the guy "obstructed" the officer, by beating him up.

Once the court concluded that the crime was, in fact, a crime in Massachusetts, it then had to decide what exactly constituted violations of the law, and whether the man in the current case committed any of those violations.

At the heart of the decision was an incident on Dec. 28, 2016, when police in Tyngsboro went to Mark Adams's house to take his guns away, at least temporarily, after the department decided to withdraw his gun license because of "a report filed by the Department of Children and Families alleging that the defendant had injured his wife and that their son was at home [at the time]."

Both sides agreed Adams was not happy with the attempt to seize his guns, although stories differed as to how he expressed that. Police said Adams tried to stop them from getting into the house and taking the guns in part by trying to close the door to keep them out; Adams said he only verbally objected and asked that they wait until at least after he consulted with his attorney, but they refused and eventually tackled him and opened his gun safe and took his weapons.

Before considering whether Adams deserved his conviction, the court first had to figure out just what the definition of "interfering with a police officer" is, starting with the fact the crime had to be "willful" - a term it defined with the help of Noah Webster's 1828 An American Dictionary of the English Language, chosen because it might have helped legislators who grappled with the whole common-law issue in an 1844 report.

But, the court continued, "willful" in this case does not include simply mouthing off, because, as the legislators concluded in 1844, that is a free-speech right "guarantied or granted by the constitution or laws."

After taking a look at how other states and federal courts have dealt with this tension between the First Amendment and police exercising their authority, the court concluded it agreed with a 1983 ruling by the West Virginia Supreme Court of Appeals that "a person does not violate the law by doing what he has a lawful right to do, regardless of whether it obstructs or hinders a police officer."

So that means that to prove the crime, at least in Massachusetts, prosecutors have to prove that the person physically stopped, or tried to stop, police from doing something - as in the case of Officer Learned in that theater in 1845.

More specifically, the court listed four specific criteria for a successful prosecution of the crime: First, a prosecutor has to show the cop or cops in the case were acting "in the lawful performance of a duty." Then the prosecutor has to prove that "the defendant physically performed an act that obstructed or hindered a police officer in the lawful performance of that duty" or made "a threat of violence" against an officer. The prosecutor also has to show that the charged person knew that the person he was talking to was a cop doing his duty and, finally, that "the defendant intended to obstruct or hinder the officer in the performance of that duty."

Based on this, the court concluded, Adams did not "interfere with a police officer," even if he was refusing a lawful demand to give up his guns:

The jury were entitled to find, in the light most favorable to the Commonwealth, that the defendant was upset and argumentative. He insisted that he

would not comply with the police order, repeatedly demanded to contact his lawyer, and told his wife not to allow the police to enter their home. The Commonwealth did not, however, establish that the defendant physically obstructed or hindered the officer in the performance of a lawful duty. Moreover, the defendant's protestations did not rise to the level of threats of violence against a police officer, which reasonably would have the effect of obstructing or interfering with the police in the performance of a lawful duty.

In the course of looking for precedents by which to guide its decision, the court searched through a database of criminal charges heard in Massachusetts district courts since 1977 - when the state began keeping such records electronically. It found 2,600 people had been charged with the offense - but that the vast majority of cases were after 1994. Why 1994? That year, the court system's administrative office issued a "a District Court complaint manual" that listed more than 5,000 different criminal charges and codified the language used for charging a person with each one: