There is no way to detect a illegal transaction.I doubt even in future this feature will ever be implemented.How can you decide if a transaction is illegal ? Volume of the trade ? Bitcoin address associated with it ? All the blockchain does is process the transactions by keeping them public regardless of who or what is being the address is used for.
Yeah sometimes blockchain check on some mysterious transaction such as what you have said. And blockchain doesn't just process transactions .
Are you talking about blockchain.info or THE Bitcoin blockchain?
If you are talking about the Bitcoin blockchain then no it does not check any mysterious transactions.
If you are talking about blockchain.info then no this..
Well as we all know that whenever we transact it always go through blockchain first.
Is not true..