Researchers obtained rosters from police officers and looked them up on Facebook, according to the project's website.
After examining the profiles to confirm that they belonged to police officers, the public statements and comments reviewed to see if they would "undermine public confidence and trust in the police".
So far, two police authorities, a sheriff office and a law firm have announced that they are acting:
On Thursday, the Dallas Police Sgt. Warren Mitchell announced that the department conducted an internal investigation following the Plain View Project, "to determine whether officials violated the department's social media policy or any other departmental policy."
Mitchell said the department is working with the project's founder to get the list of names and posts of staff affiliated to the Dallas Police. The internal study results will be published, Mitchell says.
"We take these matters seriously and we want to ensure society that we will not tolerate racism, bigotry or hatred of any kind in our organization."
Lake County, Florida
Lake County Sheriff's Florida Office said it examined social media submissions by 1
Lt. John Herrell said no sheriff's office workers were suspended, fired or put on administrative leave. Many of the posts were from former or retired, Herrell said.
Social media is part of the office's background check for new rental services, he said. Philadelphia
The Philadelphia police said it had taken 72 police officers out of the street and administrated them pending an internal investigation into posts involving Confederate imagery, anti-Muslim feelings, violent rhetoric and racist comments.
An independent law firm assists in the investigation, following the Philadelphia Police Commissioner Richard Ross. Each record will be examined to see if the speech is constitutionally protected by the first amendment, he said. If it turns out to be protected, "no further steps will be taken."
The department will also review its social media policies and consult the Anti-Defamation League.
The Philadelphia Brotherhood Order for Police Visits No. 5 President John McNesby said in a statement that the officers "are entitled to a fair trial like any other citizen."
"Too many officers have been taken out of the street during a time of increased violence in our city," he added.
St. Louis Circuit's attorney Kimberly M. Gardner's office announced that 22 officers would be prevented from bringing their cases to her office because of posts made in the ordinary project.
Cases where these officers serve as primary witnesses are currently not prosecuted, according to spokeswoman Susan C. Ryan, but it is unclear how many cases affect.
"When a police officer's integrity is compromised in this way, the entire criminal system and ours compromise overall ability to pursue justice, "Gardner said in a press release.
"After a careful study of the underlying bias contained in these social media submissions, we have concluded that this bias is likely to affect an officer's ability to perform his duties impartially."
CNN has reached St. Louis Police Officers Association, but has not heard back.
CNN's Michelle Lou, Julia Jones and Carma Hassan contributed to this report.