Last week, law enforcement officers arrived in the nation’s capital by the thousands for National Police Week to honor the sacrifice of the 120 officers killed in the line of duty in 2012.

Every day, officers go to work knowing we may pay the ultimate price to protect and serve. It is a risk we all assume as part of our responsibility to keep our communities safe. It is also our responsibility to speak out when public policy changes are needed to protect the American people and our fellow men and women in uniform.

In 2011, for the first time in 14 years, gunfire was responsible for more officer deaths than any other cause including traffic-related fatalities. Guns continue to be a leading cause of death of officers killed in the line of duty; gunfire claimed 49 officers’ lives last year alone.

As we mourn those officers lost, we cannot ignore the Senate’s disturbing rejection of common-sense measures to keep guns out of the hands of criminals and the dangerously mentally ill.

Although a majority of senators supported the Manchin-Toomey amendment to expand critical, lifesaving background checks for firearms purchasers, the Senate failed to reach the 60-vote threshold necessary for passage. More policymakers must be attuned to what law enforcement faces on the ground every day. Dangerous people have far too easy access to guns as we witnessed again just this past Mother’s Day when 19 people were shot during a parade in New Orleans.

When lives are at stake, lawmakers almost always jump to action, such as after the 9/11 terrorist attacks, putting in place stricter safety and security precautions at airports. Yet, lawmakers have failed to act to prevent the gun violence that takes thousands of lives each year.

It is irresponsible and reckless to allow purchasers to acquire lethal firearms without first passing a background check. Yet we only require checks when purchases are made through a federally licensed dealer. It is estimated that up to 40 percent of firearm transactions occur through other channels and thus bypass any check. We would never create a special line at the airport allowing 40 percent of passengers to evade security screening.

The Manchin-Toomey amendment and HR 1565, the identical House bill introduced by Reps. Peter T. King, R-N.Y., and Mike Thompson, D-Calif., will go a long way in preventing dangerous individuals from obtaining firearms by extending the background check requirement to gun shows and to postings online and in publications. This measure will also improve checks by encouraging states to report all disqualifying information to the National Instant Criminal Background Check System, ensuring that all prohibited purchasers are in the system.

Background checks work. Since the Brady Law’s enactment in 1994, more than 2 million felons and other dangerous purchasers were stopped from obtaining firearms through licensed dealers. Some opponents of extending background checks have claimed that checks don’t work because not all the prohibited purchasers who are blocked from buying guns are then prosecuted. It is utterly ridiculous to suggest that stopping millions of dangerous people from getting guns is not an enormous success. Whether there are subsequent prosecutions is a wholly separate matter.

Nine law enforcement leadership groups have united together through the National Law Enforcement Partnership to Prevent Gun Violence and, like 90 percent of the American people, favor requiring background checks for all gun sales. Policymakers have a responsibility to listen to the experts in law enforcement and an opportunity to reflect the will of their constituents by supporting a measure that will save countless lives.

It is too late for the 49 officers and other victims who lost their lives to gun violence last year. But it is not too late for us to act to better protect those who continue to put on the uniform every day and the communities they serve. It is time for more lawmakers to step up and demonstrate they have our backs.

Jim Johnson is chief of police in Baltimore County, Md., and chairs the National Law Enforcement Partnership to Prevent Gun Violence.