Leap-year babies

http://www.straightdope.com/classics/a960209.html

OK, the answer given is all very well and good, but what about the cold eyes of the law, which don’t take into account what time you’re born? Johnny, for example, born 30 September 1990 at 3.51pm, will legally be considered 10 at midnight (i.e. 0000) 30 September 2000.

What about Johnny’s brother Jack, who was born 29 February 1980? Will he reach legal drinking age (assuming 21) on 28 February or 01 March 2001? I asked some friends and they said, with authority, 01 March. Jack’s got his heart set on 28 February, though, so should I try to persuade him to wait a day for his big bash at Magnolia Mulvaney’s? (Let’s throw in the condition that, on Wednesdays [e.g. 28 February 2001], they have a better line-dance instructor.)

For that matter, in the eyes of the law, would a person born on February 29, 1980 come of age on the same date as a person born the day after? That would seem silly to me: They’re both the same age, but one’s a day older. On the other hand, the law really is silly, sometimes.

At the supermarket they sometimes have signs at the cashiers stand they say you can buy alcohol if you birthday is before today’s date 1979. Strangley that year keeps creaping up as time goes by. So I would say march 1st not Feburary 28th.

I know that nit-picking properly belongs to others, but midnight is the very last instant of today, not the first. The day does not have a time precisely equal to zero while it does have one precisely equal to (in military time) of 2400.

As of midnight, Sep 30, 2000, our ten year-old Johnny would have been experiencing the very last instant of his tenth birthday. The next instant he would be be forced to wax philosophical about how great his tenth birthday was.

Our other case cannot drink on the day prior to his birthday - Feb 28.

The alternative is that the person born on 2/29 comes of age on the same date as a person born the day before, right? I say, they have to wait until noon.

The problem in all of this is that the law and culture and common perception is all based on the calendar, but the calendar is only an approximation that ties the passage of time to the natural cycles of Earth’s rotation and revolutions. It happens to be a good approximation that balances out every 4th year, but in the interim there is some minor dischord that most of us overlook for the purpose of simplicity.

So while technically a full year from your official birth date (including time) may in fact fall on the nominal date before, the practical reality is that a year is the passage of the calendar, not the cycle of the Earth around the sun. In that regard, you would not acknowledge your birthday (anniversary - you really only have one day of birth and the rest are just anniversaries, but we abbreviate by dropping anniversary and everyone understands - pedantic enough for you?) until the date rolls around again. And for legal purposes, we don’t track officially documented birth times, but rather use the designation of midnight as the official rollover time for each date, and thus that is the legal demarcation line.

With that established, it is a simple step to realize that a leap year birth person is not legally of age until midnight on March 1, because he is not 21 until after the end of Feb. 28 th, which happens to transition directly to March instead of remain Feb. 29.

But hey, it’s fun to play the time discrepancy/calendar break-down game for the consternation it poses to people trying to come to grips with the fact that the calendar is wrong 3 years out of every 4. :wink:

We all have to endure one year of 366 days between birthdays in every cycle of four years. Leapdaters can do it the first year of the cycle, or the last. It’s up to them, really–except for legal purposes, it’s usually specified as the first.

A point I meant to make but forgot, about celebrating birthdays. They can celebrate their birthday any time they want, the same as the rest of us.

How many times have you or someone you known postponed a birthday party by 2 or 3 days to have the big bash on a weekend (Saturday or Saturday night) so you can do something special like have a bunch of friends over, or stay up late, etc? I celebrated by 17th birthday a week early because I was away from home during the actual event. The birthday party can be held anytime you want. I’ve even heard of half-birthday parties - someone with a birthday in December felt it inconvenient to share the birthday with x-mas, so they celebrated 6 mo’s off for the big party, and thus spread the gifts across the year.

Regarding Jack, he should hold his party on the first - as the legal requirement for age for drinking won’t be met on the 28th.

Well… I’m using the convention that designates 0000 as the beginning of the day and 2400 as its ending.

No problem with calling the very first instant after midnight 0000 since no one can actually measure the tiny moment that makes that period up. It’s just not midnight anymore! You have to wait 24 more hours for midnight to occur again.