To judge whether or not a financial instrument is halal according to Islamic theology is a very complex issue. While the basics of the "halality" is clear, no interest and investments according to profit participation, when faced with having to apply Islamic Jurisprudence and theology to some of the very complex project financing or fixed income structures, stronger men than me have quivered.
So it is not surprising that people are complaining that there are only about 50 to a 100 odd bunch of scholars who seem to be the sole population in the world capable of judging whether an investment or instrument is Sharia compliant. This is pushing up the price of these scholars into the millions of dollars per transaction.
More importantly, there seems to be a question of inconsistency. What one scholar says, another may negate. And who is to judge whether Scholar A is right or Scholar B is right? Certainly not me, but if there is even a slightest doubt on the instrument, it will be almost impossible to sell, syndicate or list. And you cant establish national regulatory structures which vary by scholar or what side of the bed he woke up!. So this is going to be a bit of an issue going forward. Here's a story on it.