I imagine it falls under the weights and measures clause, considering the clock is how we measure time:

> To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;

It is a power granted by the “weights and measures” provision of the constitution (or so interpreted). Read the first paragraph the history section of this Wikipedia article for more details:

https://en.wikipedia.org/wiki/Uniform_Time_Act

That actually makes a lot of sense. Thanks!

Do you think a city should have the power to ignore daylight savings time entirely, or should the state have the power to regulate all its cities? Where do you draw the line?

In practice, I imagine if California passed a state amendment fixing themselves to PST, the federal government would either change the law or refuse to enforce it. Opposing such an amendment would be pretty unpopular.

But in theory, the federal government does have power to "fix the Standard of Weights and Measures" nationwide. I see no reason for a court to rule this as being outside federal jurisdiction.

Many border cities observe the timezone of the closest major metro, even if they are supposed to be on the same time as the rest of the state.

West Wendover, NV (for instance) follows Mountain Time to synchronize with nearby Salt Lake City. So far as I know, they never asked for federal permission.

For what its worth, the relationship between cities and their state is very different than the relationship between the states and the federal government. There has historically been a concept referred to as dual-federalism which has evolved into cooperative federalism to describe this relationship. This is in contrast to the creation of cities and towns, which are entirely creatures of the state governments.

That said, I do agree the regulation of DST definitely falls under the weights and measures clause. We can't have Shelbyville continue to operate on metric time, we here in Springfield gave up on that years ago. One might even be able to successfully argue an interstate commerce argument on standardizations of timekeeping.

No. I don't believe that. I believe that states, not the federal government, are the ones allowed to make those decisions according to the Constitution.

However the weights and measures stuff makes sense and is something I completely overlooked.

Nor do I. But I also have trouble believing that, were California (or any other state) to change timezones, abolish DST, or whatever combination thereof, that the federal government would have any power whatsoever to do anything about it.

Interstate commerce clause. It's been the reason for many the Congressional abuse, and it would be my go-to for any time I ask, "why can't the state(s) just tell the Feds to piss off?"

"Because in some infinitesimally small way, someone might lose money."

I don't personally smoke weed, but I'm still incredibly offended that the Supreme Court ruled that the feds can prevent you from growing your own personal supply because of the negligible impact it might have on interstate prices.

Others have addressed the federal government's legal right to set standards of weights and measures, but I just want to add that there's a legitimate interstate commerce argument as well. Prior to the application of time zones, train schedules were nearly impossible to keep consistent as every town had it's own 'time zone' being aligned to their solar noon.

Time is already crazy for programmers and logistics, but imagine it being essentially a continuously changing band with longitude with slight local variations. The modern economy relies on a sane, more or less consistent view of time.

200 years of arguing about state versus federal power/rights/law?

It's very possible that if a state decided to do this, and the feds tried to stop them, the state would win in court. But court is expensive, and it adds to a long list of "reasons why this might be more trouble than it's worth".

Probably some interstate commerce clause justification.

Time zones were invented in order to standardize railroad time schedules, so that's probably exactly what it is.