Two certification schemes for transactions in distributed database systems are proposed. the schemes do not construct any conflict graph but use system wide unique timestamps to serialize certification requests of concurrent transactions. in the first scheme the distributed certification scheme the distributed certification scheme transactions are assigned timestamp when they request for certification. A transaction get certified if at no site its certification request conflict with that of a transaction with higher timestamp in the second scheme the negotiated certification scheme, the system negotiates with participating data items and comes up with a timestamp if possible with which the transaction will not café any conflict with concurrent transactions and will get certified the two-phase commit protocol can very easily be integrated with ether of the two certification schemes and it is shown that the schemes do not need any extra message cost to guarantee failure atomicity.