At 9 AM on Sept 11 2001, I was at my dentist’s office on New York’s east side getting my teeth cleaned. I already knew that a plane had plowed into one of the towers of the World Trade Center, although I had no idea it was anything but a horrible accident. But rumors and reports were coming in as I sat in the dentist’s chair. When I heard that the Pentagon and the U.S. Capitol had also both been hit by aircraft, I pulled the paraphernalia out of my mouth, got up, ran out, and returned to COMMENTARY’s office nearby to watch the action unfold on television.

Many things happened over the ensuing days. One of the more mundane ones was my return, a week later, to my dentist’s office. Two things stand out from that visit.

My dentist, like a great many other Americans, was in a state of outrage. “Nuke’em all” was what he said, and his favored target was Saddam Hussein. In the six years since I’ve seen him twice annually, and, because he tends to lecture me about politics—he is an avid Left-liberal—as he is working on me and I can’t immediately reply, I have had occasion afterward to remind him of what he said after 9/11. He affects to have forgotten. The only person he wants to nuke today is George W. Bush.

The other equally pertinent memory of my post-9/11 visit is the story my dentist told me on that day. On 9/12, it seems, a team of federal agents had descended on his office and asked permission to set up shop there. Directly across the street, on the same floor, was (and is) the Islamic Society of Manhattan. The feds, he told me, installed a ton of equipment in his office, some of which seemed to be able to peer through walls.

Whether that was really what the agents were doing and whether they had a warrant for it, I do not know. But the issue of U.S. counterterrorism agents peering through walls is now very much a live one. Yesterday’s Wall Street Journal reported that the full panoply of foreign-intelligence collection systems is going to be made available to domestic law-enforcement and counterterrorism agencies. Some of the equipment that will now come on line can indeed peer through walls and do other fancy things. This is welcome, even overdue, but there are legitimate privacy issues that need to be addressed.

The 4th Amendment to the U.S. Constitution states that the “right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated.” Is the use of electronic equipment to peer through walls without a warrant an “unreasonable” search? It would appear so—or at least this is how the United States Supreme Court ruled in case involving the use of electronic equipment to monitor excess heat coming from the home of a suspected marijuana dealer.

In Kyllo, Justices Stevens, Rehnquist, O’Connor, and Kennedy dissented. But Justice Scalia wrote the majority opinion holding that when the government “uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a ‘search’ and is presumptively unreasonable without a warrant.” Of course, the Islamic Society of Manhattan is not a “home” but an institution and different rules apply.

We will be hearing a great deal about Kyllo in the days to come. It was decided on June 11, 2001. How would the Justices have ruled, one wonders, exactly four months later?