|New State Senate Districts|
The Indiana Senate though takes the position that the districts took effect as of July 1, 2011 and now state senators are representing people in the newly-drawn districts rather than those people who just elected them in November of 2010. As a practical matter, this works for the Senate because there are no open new Senate districts and no incumbents were lumped together in districts. The House map though features open districts and incumbents who have been lumped together in the same district. So representing new districts wouldn't work well for House members.
I have to say, I've always thought the House interpretation was the correct one. But I never considered the problem with the State Senate which has staggered elections. Senators serve four year terms with half of the body elected every two years. So only 1/2 the Senators will be elected from the newly drawn districts in 2012. The rest will have to wait until 2014. If you apply to the Senate the House theory (that legislators don't start representing the new districts until they are elected from those districts), after the 2012 elections you'd have half the Senators representing new districts and half representing old districts. Thus there would be parts of the state that had two senators and parts of the state that had no representation in the Senate.
I'd be curious to know what the correct answer is to this legal/political riddle.