CASCADES OF COMMENTARY still course through the airwaves and cyberspace about the trial of George Zimmerman for killing Trayvon Martin – a legal process that in its end last week achieved the very opposite of settling matters.

So much has been written and said — much of it aimed at influencing Attorney General Eric Holder into deciding now on the exercise of federal powers over the killing — that I’m simply stepping back. No more words, surely, are needed. Instead (but still kind-of related) let’s consider terrorism.

Holder does have another decision to make soon — sometime over the next 65 days, in fact. It’s about the next high-profile death trial that is bound to provoke wall-to-wall media commentary. On September 23, Dzhokhar Tsarnaev — now 19 but by then 20 years old — will return to court to face charges of, among the 30 counts against him, using a weapon of mass destruction resulting in death, and killing a college campus police officer. Holder has to decide, amid calls that are mounting to a crescendo, whether or not to seek the death penalty.

Another uncertainty that might, just might, get clearer when Tsarnaev is tried, is whether he rightly belongs in what President Barack Obama proclaimed to be a new category of terrorist, saying to White House reporters, “One of the dangers that we now face are self-radicalized individuals who are already here in the United States.”

Commenting from afar, the head of Britain’s premier military and security think-tank, Michael Clarke at the Royal United Services Institute, recently gave me a blunt, maybe a bit superior-sounding, assessment of American approaches to this question of so-called “home-grown jihadism”:

“The United States has been behind us in this respect. The U.S. has always regarded Jihadist terrorism as something that comes at it from the outside, but it doesn’t. You’ve got to swallow a bit of pride and say, yes, we have a homegrown problem.”

For its part, the UK has without doubt had plenty of experience of fighting terrorism coming from within — some of it indeed with an element (though it’s not to be overstated) of religion-based motivation behind it. The last three decades of the 20th century saw the predominantly Roman Catholic IRA (Irish Republican Army) planting deadly bombs in both Northern Ireland and Britain to further their campaign against the British authorities and their (mainly Protestant) loyalists in the disputed province.

Peace agreements have turned those bombings into somewhat distant memories now, but the new century then brought suicide bomb plots by young Muslim men of British nationality. Most horribly there were the attacks on London’s Underground transit system and a city bus on July 7, 2005, which killed 52 people and injured about 700.

EVEN WITH ALL THE CHATTER  here about a wholly new chapter opening in America’s terrorism experience, I’ve seen no serious mass media attempts to examine other nations’ experience for any useful comparison. I had my own opportunity, though, when PBS sent me to my old home country to investigate the British authorities’ efforts at countering their internal threat. My report is being aired on the Religion and Ethics Newsweekly program over this weekend. (Days and times vary, by locality. — WATCH IT HERE, or above on this page).

I zeroed in on one of the British government’s strategies, which it calls “PREVENT,” and which it claims has successfully identified and diverted several hundred angry young Muslim men away from a path of violence.

You can follow all the details of my exploration on air or online… but it will likely come as no surprise that — despite evidence of some UK victories for peace over mayhem — nobody thinks that all internal terrorism can be thwarted.

Even the bullish Michael Clarke admits in the report that if the Boston Bombers had been planning their attack in Britain, they would probably have been “so low down the threat spectrum that they would not have triggered a PREVENT intervention.”

And Clarke summed up: “Prevent strategies cannot prevent everything.”