Last week, Congressmen Jerrold Nadler (D–NY), Edward Markey (D–MA), and Bennie Thompson (D–MS) publicly chastised the Department of Homeland Security (DHS) in a New York Times op-ed, claiming that DHS has done little to counter the terrorist threat to maritime cargo security in recent years.

While this couldn’t be much further from the truth, through their thin and misinformed arguments they certainly made one thing clear: When it comes to maritime cargo security Congress still doesn’t get it.

Five-years ago, Congress passed the Implementing Recommendations of the 9/11 Commission Act, which included a mandate that DHS scan 100 percent of maritime cargo entering the U.S. by July 2012. In other words, Congress sought to require that each of the approximately 11.6 million maritime cargo security containers entering U.S. ports each year be physically scanned or inspected.

This mandate made little sense from day one. Not only was 100 percent maritime cargo scanning never a recommendation of the 9/11 Commission, as Congress claimed, but the mandate failed to recognize supply-chain realities. Today’s economy relies heavily on the timely and efficient movement of goods. The logistical delays and bottlenecks caused from the implementation of the maritime cargo mandate would therefore by stifling.

Not to mention the fact that while majority of cargo traveling through the maritime supply chain consists of legitimate goods, the 100 percent maritime screening mandate treats every piece of cargo as a genuine threat.

Supply-chain realities aside, the bigger issue is that 100 percent scanning, contrary to the claims of some in Congress, simply does not equal 100 percent security. DHS’s “layered, risk-based approach” to maritime cargo security is far from “inadequate.” In fact, this is exactly the approach DHS should continue to take.

By evaluating cargo’s threat level based on manifest information, such as origin and content, DHS can focus its resources on cargo deemed to be “high risk” for secondary screening. Recognizing this fact, DHS announced last month that it had “concluded that 100-percent scanning of incoming maritime cargo is neither the most efficient nor cost-effective approach to securing our global supply chain” and that it would not meet the July 2012 mandate.

At least DHS gets it. Now if only Congress could see the reality.