As I recall, Jack mostly uses Krav Maga, with some other CQC techniques mixed in. I don’t think we’ve actually talked about Krav Maga yet; it’s a modern combat style designed by the Israeli Defense Force, which focuses on very close quarters combat. It’s a little strange that a Federal Agent would be using them, but, it isn’t completely unreasonable. The style was very popular for a few years back in the early 2000s, and you can still find schools for it in the US.
It’s one of the few actual combat styles that you can get training in “off the street,” though the civilian version is probably about ten years out of date.
Now, as much as I love 24 in a minute to minute context, there’s a lot of stuff in its background that just doesn’t work.
CTU is supposed to be a military or CIA operation. Before the Department of Homeland Security, domestic counterterrorism was a bit of a bureaucratic mess. Theoretically the FBI had jurisdiction, and if it was a bombing, they were the ones called in to investigate. After 9/11, the DHS was set up to coordinate intelligence gathering from the CIA, NSA, and FBI, to assist in the prevention of future terrorist attacks. It outright consumed a few agencies, including the Secret Service, ICE, and, I think, the DSS.
In theory, the CIA has never been allowed to operate domestically; the same is also theoretically true of the NSA. Now, that’s never really been the case, domestic actions by the CIA go back at least to the 1950s, and Echelon, an NSA surveillance network, dates back to the mid 60s. Obviously, this stuff goes down the rabbit hole fast, but the critical thing to take away is that, even after the PRISM leaks, the CIA and NSA aren’t allowed to operate openly on US soil. Meaning, at least in the world we live in, CTU would be a legal impossibility.
If you’re writing a counterterrorism agent in the federal government, today, you’re looking at FBI or DHS. DHS’s primary interest is supposed to be sharing intelligence, not acting on it, so really, if you want a Jack Bauer type counterterrorist investigator, you’re probably looking at a Special Agent in the FBI.
If you want the specific requirements for a character to be an FBI Special Agent, I could rattle what I remember off the top of my head, or just link this: https://fbijobs.gov/114.asp
The short version is, no serious physical impairments, including colorblindness, or less than 20/40 vision, no serious criminal record, at least a four year degree, between the ages of 23 and 37 (when they’re recruited). But, that link goes into some interesting details. (Also, question 17 still cracks me up, until I remember that it really was one of the most common questions they were getting for years.)
What it doesn’t cover is that military service, or a background in law enforcement is a plus. It’s not technically necessary, but a character who didn’t serve, and wasn’t a cop, will be somewhat socially isolated. As far as I know, this isn’t malicious; it’s just that the Agent in question won’t have the same shared experiences to help with making friends and networking.
The FBI does their hand to hand training at Quantico. I don’t have any real details on it, but it’s safe to assume it’s a fairly standard police hand to hand variant. Given recent trends in police tactics, it’s entirely possible that it’s started incorporating military hand to hand techniques.
If you want to avoid the FBI for some specific reason, all of this is still a pretty reasonable baseline for any federal agent.
Jack’s background in Special Forces is, let’s call it “difficult to justify”. Ex-Special Forces has become a flashcard for badass, but, as with a lot of things, it tends to get massively misunderstood by people on the outside. I’ll probably come back to this at a later date, but, in general, people who come out of the Special Forces programs aren’t really well suited for jobs in law enforcement. Most often, this is used to designate a character as trained in combat, just like, literally, everyone that serves in the Armed Services.
My final advice on writing a character like Jack Bauer is; don’t. The only reason Bauer works at all is Kiefer Sutherland’s performance; he’s walking a very fine tightrope to keep the character likable. On paper, without an actor to kludge the character into line, that’s going to be a very difficult mark to hit.