As the trial to make sweeping reforms to stop-and-frisk enters its fourth week, those taking the stand this week include academic scholars offering their expert analysis on the practice, former NYPD chiefs and commanding officers.

On Monday, Dr. Eli Silverman, professor emeritus at John Jay College of Criminal Justice and the Graduate Center of CUNY, and professor John Eterno, who didn’t testify, presented two extensive surveys of NYPD retirees concerning pressure to increase stop-and-frisk, summons and arrest numbers, with findings published in 2008 and 2012.

Silverman’s surveys reveal that pressure mounted for NYPD officers to make more arrests after the city implemented the COMSTAT system.

Former Chief of Department Joseph Esposito took the stand on Tuesday, and attorneys questioned whether officers who used racial profiling as a factor for stop-and-frisks were tracked. Esposito said that stops are signed off on forms by supervisors and that racial profiling was not used, claiming that reasonable suspicion was the reason.

Attorneys pointed out a 40 percent increase in stop-and-frisk under Esposito’s watch. However, the former chief pointed out that the city saw a decrease in crime during his tenure as well.

Also taking the stand was Charles Ortiz, a former commander of the 43rd Precinct. Ortiz was commander during the time plaintiff David Floyd was stopped in February 2008. Donald McHugh testified as well. McHugh, a former commander of the 41st Precinct and currently the head of the NYPD’s World Trade Center Command, is one of the people heard on Officer Adhyl Polanco’s roll call recordings.

Last week, representatives of local and national organizations, elected officials and family members of people killed by the NYPD gathered in front of Daniel Patrick Moynihan U.S. Court to express support for the historic stop-and-frisk lawsuit taking place inside. Those present called on the NYPD to put an end to stop-and-frisk abuses, which they say can lead to more extreme violence and death. They also condemned the police actions that led to the deaths of Malcolm Ferguson, Sean Bell, Ramarley Graham, Reynaldo Cuevas, Noel Polanco, Kimani Gray and others.

“African-American and Latino/a people are stopped-and-frisked so often for no reason. The police have already labeled us all as criminals,” said Valerie Bell, mother of Sean Bell. “Stop-and-frisk is an invasion of our privacy as human beings. We are all human beings. The only difference is the color of our skin.”

“Stop-and-frisk kills people. Too often young people turn and run because they are afraid of being stopped. Stop-and-frisk causes fear and this leads to dangerous situations. It needs to stop,” said Margarita Rosario, mother of Anthony Rosario and aunt of Hilton Vega, who was killed by the NYPD in 1995.