So I'm a law student with an interest in energy regulatory law, and I've done a fair amount of digging on the ALJ clerkship front. Basically, FERC clerkships have some upside, but some major cons as well.
On the positives, nearly every energy lawyer I've spoken to (mostly at firms, some at DC trade associations) speaks very highly of attorneys who started out as FERC ALJ clerks. They all seem to think it's a great way to get experience, particularly on the settlements/arbitrations that crop up all the time in electricity and natural gas markets.
On the downside, there are a few problems/oddities relative to other clerkships.
1. FERC ALJ clerks are hired for fixed two-year stints - but the entire batch of 7 clerks usually rolls over on the same cycle. My understanding is that the current cycle is on even years, so current 3Ls (c/o 2012) and 1Ls (c/o 2014) will have a crack at them, but current 2Ls (c/o 2013) are SOL.
2. There are some
very restrictive ex parte rules. This means that while you're working as a clerk, you can't interact with/converse with/breathe near other energy regulatory attorneys. Goes for internal offices (like FERC enforcement or GC's office), but it also goes for external law firms. I may be wrong on this, but I got the impression that ALJ clerks are not allowed to hold an offer open at a firm for 2 years down the line - so the ALJ clerkship basically turns into a bet that you'll be more marketable/valuable after those 2 years, but it won't be a sure thing. One of the pages below indicates that you're not even allowed to interview for jobs until you've been on the job for 22 months (out of 24).
3. I've also heard that at the depths of ITE, ALJ clerks were simply not being hired by firms. Things may have improved since then, but apparently in some instances ALJs allowed their clerks to stay on for a third year rather than get thrown out in the cold with no job. (This reinforces downside #2 - no holding offers at firms. How it affects downside #1 - the 2-year cycle - I can't say).
So, all in all, my understanding is that if you have an SA at a firm with a good energy regulatory practice, returning to your firm after graduation is probably a safer bet. In particular, if you stay for a few years you might be able to lateral over to FERC's enforcement office, which apparently is super-busy these days (and seems unlikely to change in the near future). On the other hand, for people who don't have biglaw offers, a 2-year ALJ clerking stint could be a good way to boost their industry knowledge, and would likely - but not definitely - lead to a job at FERC or at a firm down the road.
For more info on the actual hiring timeline, see:
http://www.lclark.edu/live/files/5395-2 ... hip-manual
http://www.chapman.edu/law/_files/caree ... nginfo.pdf
http://www.law.wvu.edu/r/download/22816 (Looks like they were hiring in 2009, so I'm not sure how that impacts the 2-year pattern)