If many federal employees and contractors start feeling as if they’re being watched more than ever, they can thank Aaron Alexis for that.

Alexis is the man officials have identified as the gunman whose shooting rampage at the Washington Navy Yard on Monday killed 12 people before he was shot dead by police.

Since then, there has been a flurry of calls to examine the security-clearance process. Alexis, a defense contractor, had a secret-level clearance. Several incidents in his background and entrance procedures for the base were not enough to stop him from taking a shotgun through the Navy Yard gates and up to a fourth-floor restroom, where he apparently assembled the weapon before the massacre.

This tragedy could mark a turning point in domestic government security, just like the Sept. 11, 2001, terrorist attacks and the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City led to security procedures that affect us all.

A Navy Yard turning point would be felt primarily by federal employees and contractors. Those with security clearances should not be surprised at attempts to take away some of their privacy in favor of greater security for government files and federal buildings.

The Big Brother possibilities are scary.

Once upon a more innocent time, anyone could walk into many federal buildings unannounced and unescorted, and proceed to almost any office. Now, even relatively sleepy federal facilities make visitors pass through metal detectors while their bags are being X-rayed.

Pennsylvania Avenue in front of the White House and several streets around the Capitol are closed to traffic.

It was a trade-off: The government took away the freedom to drive in front of the White House, for example, in exchange for greater protection against truck bombs.

Now we can expect another trade-off.

The Obama administration and Congress are looking at ways to plug any holes in the security-clearance process. It’s a move prompted by Edward Snowden, a National Security Agency contractor who used his top-level security clearance to leak highly sensitive documents to The Washington Post and other media outlets, and Alexis, whose lower-level clearance allowed him deadly access.

For people like Snowden, who work with the most secret of secrets, constant surveillance could be in the offing.

That’s what John Hamre, president and chief executive of the Center for Strategic and International Studies and a former deputy secretary of defense, advocates.

“I continue to hold special clearances, some of extraordinary sensitivity,” he said in an op-ed in Thursday’s Post. “The government should monitor me steadily because of the sensitivity of these programs, and I should expect such surveillance as a condition of my government work.”

What form would such monitoring take? Would one set of spies listen to every personal phone call made by another set of spies? And would those doing the snooping be snooped on by others? Today’s technology makes it much easier than that.

As Snowden taught us, the NSA can collect information on all U.S. telephone calls without anyone listening. I’m not recommending this, but that collection of metadata could be fine-tuned for those with top security clearances to regularly detect their phone call and purchase patterns, for example.

Agreeing to this could become a condition for top-secret personnel. They would know they would be monitored, but they wouldn’t know when they were being monitored.

For those like Alexis with lower-level clearances, the additional surveillance might mean that any run-in with the law, even over a neighborhood dispute, even with no conviction, would get much more scrutiny than it does now. Medical and mental-health records also could be considered fair game for the background checkers.

We know from Snowden’s exposures that intelligence agencies collect far more information on Americans than almost anyone realized. That naivete now sufficiently scorned, it is not a stretch to expect Uncle Sam to train his spying eyes on his staff — even more than he already does.

After Monday’s massacre, many would find no fault.

Twitter: @JoeDavidsonWP

Previous columns by Joe Davidson are available at wapo.st/JoeDavidson.