This weekend saw the biannual time change for Daylight Saving Time. With that came the normal complaints asking why Daylight Saving Time is even a thing. I’m going to be a legal nerd this week and discuss a quirk in the way the law is written, a quirk that means there would actually need to be an act of Congress in order to make Daylight Saving Time permanent.

The applicable law is found at 15 U.S.C. § 260a. It contains a great deal of legalese, but in layman’s terms the main thrust is that from the second Sunday in March until the first Sunday in November time is adjusted forward for an hour. The way existing law is written, a state can exempt itself from Daylight Saving Time—Arizona and Hawaii currently do so—but it is not possible for a state to adopt permanent Daylight Saving Time due to an express preemption section in the statute. I’m not going to perform a deep dive into the legislative history of the provision to try to discern whether this one-way ratchet was intentional or not but I suspect it probably was since the goal of legislation around time throughout American history has been increasing uniformity.

This short post isn’t a position piece and my own work schedule means I have much more control over the amount of daylight to which I am exposed than most people (regardless of the time or season). It is instead merely an explainer on why things are the way they are.