Are you sure? I know NH has a law regarding the timing of NH primary, and I know that NH, IA, NV and SC have some sort of loose agreement to shift "together" is some other state or states schedule a primary before the IA, NH pair; but yours is the first time I have read that the timing of the IA caucus is bound by some law.
Yes, it is an Iowa law that we are first in the nation.
Here is a bit of Iowa Code:
43.4 POLITICAL PARTY PRECINCT CAUCUSES.
Delegates to county conventions of political parties and party committee members shall be elected at precinct caucuses held not later than the fourth Monday in February of each even-numbered year.
The date shall be at least eight days earlier than the scheduled date for any meeting, caucus, or primary which constitutes the first determining stage of the presidential nominating process in any other state, territory, or any other group which has the authority to select delegates in the presidential nomination.
This article explains it, and yes, it is by statue that Iowa must go first. http://caucuses.desmoinesregister.com/2011/09/28/earlier-caucuses-put-bigger-focus-on-iowa-many-say/ Iowa is not happy about this. We have had no involvement in a conspiracy to shut out Palin.