The ongoing war in Mumbai will no doubt revive the debate over whether we need a Federal Investigation Agency sooner than later. While Vivek Reddy has argued here that our Constitution indeed provides for greater Central role in tackling terrorism, there are equally valid arguments why in a cooperative federalism like ours, it makes sense to involve the States on tackling federal crimes. This article in the South Asian Terrorism Portal throws light on, among other things, why we cannot ignore the States in counter-terrorism.
The point which the SATP article rightly makes is that the existing Central outfits do not inspire any hope that an addition of a Federal Bureau to tackle terrorist offences would make any difference to our current efforts. See this item on the CNN-IBN website on how the NSG arrived late in Mumbai -nearly nine hours after the first assault.
The lesson probably is that if a Mumbai-like crisis happens, Central agencies should not wait for request from the State Governments to respond. The State Government clearly underestimated the threat initially, which caused the delay in its request for Central forces. Therefore, there is a case for the Centre to step in, on the basis of its own assessment, if the State Government wavers. This is not to suggest that the State Government must be ignored, but only that the Centre must take a pro-active role, and take the State into confidence, before going ahead with its strategy. I would agree with Vivek that one doesn't need a Constitutional amendment for such a proactive role by the Centre in times of a crisis. The former NSA, Brajesh Mishra suggests a greater degree of coordination between the IB and the State agencies than what we find today.
Obviously, nothing prevents such a coordination. No one says a Constitutional amendment is required for this. B.Raman, former additional secretary, Cabinet Secretariat, also makes the case for a Central Investigating Agency, but his underlying theme is coordination between the Central and State agencies, which can be achieved even now, without going through the rigmarole of actually creating such an agency at the Centre.