A Massachusetts court has dismissed the wrongful death suit filed against Harvard and three of its employees by the mother of Justin D. C. D. Cosby.

Cosby, a Cambridge resident, was fatally shot in 2009 in the basement of Kirkland House during a drug deal gone wrong. His mother B. Denise Cosby filed a wrongful death suit in May against the University, Lowell Co-House Masters Dorothy A. Austin and Diana L. Eck, and chemistry and chemical biology lecturer Ryan M. Spoering, who was resident dean of Lowell at the time of the shooting.

The lawsuit alleged that Harvard had acted negligently by allowing the man who eventually would be convicted of Justin Cosby’s murder to live in Lowell House for months, in violation of University rules. Harvard’s lawyers had argued that the University had no duty to protect Cosby.

In a ruling obtained by the Boston Globe, Middlesex Superior Court Judge Mitchell Kaplan sided with Harvard, dismissing the lawsuit against the University and its three employees.

“There is nothing inherent in knowingly or negligently allowing a Harvard student to permit her boyfriend to stay in her room such that a reasonable person would expect visitors to the University would be protected from the foreseeable deadly conduct of the room guest,” wrote Kaplan in the nine-page opinion.

Denise Cosby’s original complaint centered around a Harvard rule that requires students to speak with their House Master before hosting a non-Harvard guest for more than two nights.

Jabrai Jordan Copney, the man convicted of shooting Justin Cosby, resided on campus for months in the Lowell House dorm room of his girlfriend in violation of Harvard rules. The Harvard College Handbook for Students, which was cited in the complaint, states that “The hosts of repeated overnight guests who are not Harvard students must make their guests’ presence known to the Building Manager and security personnel due to safety considerations.”

The complaint alleged that Harvard was at fault because the three Lowell House officials either “knowingly allowed Copney, a nonstudent, to live in the Lowell House for an extended period of time, in contravention of Harvard’s rules, and allowed him to have unfettered access to the House and the rest of Harvard’s campus,” or “negligently failed to detect Copney’s continuing, unauthorized presence.”

Harvard in September submitted a legal filing saying the University could not be blamed for Cosby’s death. Harvard’s lead attorney Martin F. Murphy stressed that point when the two sides traded arguments in court during a hearing on Dec. 19.

“Particularly [when] the plaintiff has come onto the property in order to engage in dangerous activities, the law makes it clear that [Harvard] doesn’t have that duty of safety to [Cosby],” said Murphy in December.

During that same hearing, attorneys representing Cosby’s mother argued that the University had allowed a dangerous situation to develop by not enforcing its own policies regarding guests in Harvard dorms.

“The only reason this became a situation is because of [Harvard’s] negligence,” said Isaac H. Peres, the plaintiff’s lead attorney, at the time.

According to testimony from Copney’s murder trial, he and two other men cornered Justin Cosby in the basement of Kirkland’s J-entryway on May 18, 2009. Cosby sold marijuana to Harvard students and the group demanded that he hand over the drugs he had with him. When Cosby refused, Copney shot him, prosecutors and witnesses said.

In April 2011 Copney was sentenced to life in prison for the murder of Cosby. His two companions testified against Copney in exchange for lighter sentences and both pleaded guilty to manslaughter.

—Staff Writer Matthew Q. Clarida can be reached at clarida@college.harvard.edu.