THIN BLUE LINE. WHAT IS IT IN POLICING?
“The...flag with a blue bar has become widespread in North America as a sign of solidarity and support for police,” Al McCambridge, corps sergeant major with the RCMP’s executive, wrote in a memo obtained by Global News.
https://globalnews.ca/news/7392282/rcmp-directive-thin-blue-line/
"Officers wear the patch for a deeply personal meaning, said [Calgary Police Chief] Neufeld. It symbolizes to them a reminder of officers killed in the line of duty, including most recently the death of Sgt. Andrew Harnett, in December 2020."
"The Thin Blue Line is a term that typically refers to the concept of the police as the line which keeps society from descending into violent chaos. The Blue in Thin Blue Line refers to the blue color of the uniforms of many police departments."