New York resident and peace activist Martin Gugino on Monday filed a civil lawsuit against Buffalo, New York, police after being seriously injured by several officers this past summer.

On June 4, Gugino was participating in a peaceful Black Lives Matter protest in Niagara Square when members of the city’s militarized Emergency Response Team (ERT) shoved him to the ground. According to witnesses, Gugino lay bleeding on the sidewalk while officers continued to march past him. As a result of the encounter, Gugino suffered a fractured skull and concussion that necessitated a lengthy hospital stay.

The complaint lists the city of Buffalo, Mayor Byron Brown, three police officers and two police commissioners as defendants. Among the claims, Gugino alleges that the city’s curfew was unconstitutional, that the Buffalo police have a demonstrated history of excessive and unreasonable force and that his First Amendment right to assemble was violated.

Buffalo’s ERT was formed in 2014 following protests that occurred after unarmed teenager Michael Brown was killed by police in Ferguson, Missouri. At the ERT’s unveiling in 2016, Lieutenant Thomas Whelan commented on the team’s purpose, stating “there’s a very fine line between policing and honoring people’s civil rights … [our job is] to move people, keep avenues open and remove protestors that are there to disrupt other people’s rights.” Days after the incident involving Gugino, Brown ordered a new police unit that was trained in civil rights issues to handle peaceful protests.

The complaint states:

Upon information and belief, Defendants have a policy, practice and/or custom of using, concealing, excusing and/or condoning the unlawful use of unnecessary and/or excessive force against citizens, including utilizing internal investigative procedures to exonerate the police officers who committed unlawful, violent crimes against citizens. The policy of Defendant, City of Buffalo, as set forth above, is decades old, and has not changed despite federal oversight. In 2017, the University at Buffalo and Cornell law schools released a study based on two years of research into Buffalo Police Department policing practices, which documented decades of policing abuses. Among other violations, the researchers “found that the BPD engages in a pattern or practice of … excessive use of force, particularly against individuals of color; and … retaliating against people engaging in constitutionally protected expression and lack of redress.”

Earlier this month, a grand jury declined to indict officers Aaron Torgalski and Robert McCabe with the charge of felony assault against Gugino.