In presidential elections, voting in certain states repeatedly predicts the outcome of a race nationally. Ohio and New Mexico, for example, tend to cast their electoral votes for the candidate who eventually becomes the winner of the election. Political analysts refer to these states as bellwether states.
The term bellwether refers to the practice of placing a bell on a male sheep who leads the flock, but for those of us who aren’t shepherds, the word is most commonly used to mean a “predictor” or “indicator.”
Essentially, bellwethers predict outcomes, and they exist in many fields outside of politics (and sheep). They’re increasingly common in our legal system, and bellwether trials can either breathe life into future lawsuits, or they can deflate litigation.