[LEAPSECS] "China move could call time on GMT"

[Ian Batten]

On 1 Jan 2012, at 0024, Poul-Henning Kamp wrote:


> In message <1112311843.AA15967 at ivan.Harhan.ORG>, Michael Sokolov writes:

>> =?iso-8859-1?Q?Ask_Bj=F8rn_Hansen?= <ask at develooper.com> wrote:

> 

>> LEGAL things would break.  What the people like you fail to grok is

>> that some of us are bound by *non-negotiable legal requirements* to

>> live our lives on a time standard that's anchored to Mean Solar Time.

> 

> Who are ?

> 

> Please cite relevant laws...


Quite.  

In the UK, at least, there's a layer of indirection which makes all the claims of doom if UTC is unhitched from UT1 slightly hysterical.    The sole legislation which explicitly hooks UK legal time to "GMT" is the Interpretation Act 1978, S.9:


> Subject to section 3 of the Summer Time Act 1972 (construction of references to points of time during the period of summer time), whenever an expression of time occurs in an Act, the time referred to shall, unless it is otherwise specifically stated, be held to be Greenwich mean time.


That's it.  That can probably be extended through to make "GMT" the default interpretation of times in contract law.  Although a non-government bill ran around the houses in 1996 without resolution to change this to UTC, that was not because of some fundamental legal difficulty: re-defining "GMT" (as used in the Interpretation Act 1978) to be UTC, or alternatively amending the Interpretation Act 1978 to simply say "UTC" (or something else) would hardly be the the stuff of political nightmares.  A few Tory backwoodsmen might start howling about straight bananas and metric martyrs, but it wouldn't take more than half an hour of parliamentary time to do, if indeed it couldn't be done with a statutory instrument or a suitable piece of case law being made.   For a start off, "GMT" doesn't exist as a practical realisation any more, and custom and practice says that "GMT" and "UTC" are, from a legal perspective, interchangeable.  Once that change is made, all legislation going forward swings behind whatever timescale is adopted.

A lot of the rest of the "ah, it has to be mean solar time" claims are nonsense.  Lighting Up Time, for example, doesn't require Mean Solar Time, it requires local apparent solar time, so both location and the equation of time enter into the calculation.   And in any event, the Road Vehicles Lighting Regulations 1989 could be amended easily, being regulations, to reflect any change (which wouldn't arise, as the regs just say "sunrise" and "sunset", meaning local actual).

ian