A technique for evaluating fraud risk in e-commerce transactions between consumer and a merchant is disclosed. The merchant requests service from the system using a secure, open messaging protocol. An e-commerce transaction or electronic purchase order is received from the merchant, the level of risk associated with each order is measured, and a risk score is returned. In one embodiment, data validation, highly predictive artificial intelligence pattern matching, network data aggregation and negative file checks are used. The system performs analysis including data integrity checks and correlation analyses based on characteristics of the transaction. Other analysis includes comparison of the current transaction against known fraudulent transactions, and a search of a transaction history database to identify abnormal patterns, name and address changes, and defrauders. In one alternative, scoring algorithms are refined through use of a closed-loop risk modeling process enabling the service to adapt to new or changing fraud patterns.