People
Law and order exist for the purpose of establishing justice and ... when they fail in this purpose they become the dangerously structured dams that block the flow of social progress.
— Dr. Martin Luther King Jr.

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Law and order, the writer argues, are only worth having if they deliver justice. When they don't, they stop being useful structures and become dams, holding back the current of social progress instead of guiding it. The metaphor pictures rigid rules as barriers against a river of change.
Context reviewed