Your opinion here leads me to believe that you are beyond help and live in a state of crippling idiocy.
But... I'll ignore that and go ahead and comment anyway. Legally, you can't punish people retroactively. Why? It's a Constitutional amendment found within the bill of rights (more specifically the 5th Amendment) that prevents double jeopardy.
From the Wikipedia article:
"The double jeopardy rule arises from the Fifth Amendment to the United States Constitution, the relevant clause of which reads:
"... nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb ... "
This clause is intended to limit abuse by the government in repeated prosecution for the same offense as a means of harassment or oppression. It is also in harmony with the common law concept of res judicata which prevents courts from relitigating issues which have already been the subject of a final judgment."
I don't know why there's a prior to 2006 stipulation to their ruling, other than perhaps another law that requires ALL sex offenders to wear GPS.
Anyway, I personally think the entire thing is retarded. Sex offenders shouldn't be permanent second-class citizens simply because of their unfortunate and nearly unchangeable fetish. I don't agree with registering sex offenders for public notice, I don't agree with GPS tracking devices, none of that shit. However, if you're convicted of raping a child, I do believe that your testosterone should become forfeit. State repossesses your balls, you're not aggressive nor inclined toward sexual pursuits whatsoever, you don't have to be tracked for your whereabouts, everyone's happy.
