“Proportionality” has quietly become one of the most important ideas in modern law. From free speech and data privacy to environmental regulation and national security, judges across the world use this doctrine to decide when rights can be limited and when the state has gone too far. But what does it really mean to be proportionate, and why does this idea matter more than ever in a divided age?

Once a financial checklist for mergers and acquisitions, “due diligence” has evolved into a legal duty to prevent harm - from human rights abuses to environmental damage. This article explores how the concept has expanded from boardrooms to courtrooms, redefining what responsibility means for modern business.