TBL meaning in Governmental ?

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.

The phrase originated as an allusion to the British infantry regiment The Thin Red Line during the Crimean War in 1854, wherein the regiment of Scottish Highlanders—wearing red uniforms—famously held off a Russian cavalry charge. Its use referring specifically to the police was popularized by Los Angeles Police Chief Bill Parker during the 1950s; author and police officer Joseph Wambaugh in the 1970s, by which time "thin blue line" was used across the United States; and Errol Morris's documentary The Thin Blue Line (1988).

The "thin blue line" has been appropriated by the "Blue Lives Matter" movement, which began December 2014, after the homicides of NYPD officers Rafael Ramos and Wenjian Liu in Brooklyn, New York in the wake of the homicides of Eric Garner and Michael Brown Jr earlier that year and in the context of the greater Black Lives Matter movement. The "thin blue line" has also been associated with white nationalists in the US, particularly after the Unite the Right rally in 2017.