Many teams rely on traditional code coverage metrics—like line or branch coverage—to measure how thoroughly their software is tested. But in safety-critical domains such as aviation, healthcare, medical devices, automotive, and industrial automation, those metrics aren’t enough. This is where MC/DC coverage (Modified Condition/Decision Coverage) becomes essential.

MC/DC requires every condition in a decision to be shown to independently influence the outcome. Instead of only checking whether code paths are executed, it validates whether each boolean condition actually impacts the logic. This level of scrutiny catches subtle logic failures that other coverage types tend to overlook, especially in decision-heavy modules such as fault detection, emergency overrides, authentication logic, and risk evaluation algorithms.

What makes MC/DC so valuable is its ability to expose hidden risks early. For example, a system might have 100% branch coverage yet still hold a bug because one condition never truly affects the decision—even though the branch was executed. MC/DC prevents that false sense of reassurance.