I think the Supreme Court gave a good and legally correct decision in cancelling the coal block allocations.
The law on this point is very simple. So far as one's private property is concerned, one can deal with it in any manner ( provided no law is broken). Hence one can give away his private property to any one he likes, or deal with it in any manner.
The position, however, is very different in the case of public property or property belonging to the state. Here Article 14 of the Constitution, which guarantees equality, applies. Hence to give away public or state property ordinarily requires open public auction or public tender after advertising it in well known newspapers having wide circulation, so that everyone can apply, and it should be given to the highest bidder. This alone ensures transparency and fairness, and compliance with Article 14.
The coal blocks in question were given away surreptitiously without complying with the above procedure, causing heavy loss to the public exchequer, apart from violation of Article 14 of the Constitution. Hence the Supreme Court was perfectly correct in cancelling the shady deals.