There is a much overlooked legal aspect to the HCJ decision to declare "CHOK TAL" exempting (mostly) the Ultra Orthadox from army service. This aspect isn't in the result, but rather the legal process used to achieve it. The court's decision was based on its finding that the law was not capebale of fulfilling the aim for which it was legistlated - and as such the discrimination present in the law was not proportional to its injustice. This has been used several times in the past (though not as many as people think). However the recent decision really changed the rules - because the legality of the law, was decided not based on the wording of the law, but based on its exectuion. In other words, the court decided that the law was not properly balanced, based on the low rate of Ultra Orthadox men enlisted since the law was legistlated.In the past all decisions to declare a law illegal, were based on an analysis of the law at the time it was legistlated.
This is a huge change. It immediatly widens the scope of laws that can be attacked in the future - in essence every law which isn't fulfilling its true purpose can now be attacked. Additionally the time frame for the declaration of a law as illegal has widened significantly. In the past, those turning to the court for relief, had to rush to court as soon as the law passed in the Knesset. Now, they may want to wait a few years inorder to gather the necessary evidence.
I believe that what the court inteded to state was that the "TAL LAW" was not a sufficent answer to the injustice inherent in he haredi [ultra-Orthodox] evasion of serving in the IDF. In other words, "TAL" was a failed attempt to solve an injustice. However, being a failed law, should not have made it illegal. It just makes it - a failed law. What the court wanted was for the Knesset to try again.
So why did the court go ahed and declare TAL illegal, and not just state its opinon that it is legal, but insufficent? Politics. If the law was legal, the Knesset would have little motivation to change it. If you create a vacum - the Knesset has no choice but to fill it.