From the article:
It is queried for phone numbers of interest mainly using what are called “administrative subpoenas,” those issued not by a grand jury or a judge but by a federal agency, in this case the D.E.A.
In other words, no, there's no oversight. The DEA issues its own legal requests. The AT&T "contractors" who issue the queries sit next to the agents and are paid for by the DEA (in other words, they're employees of the government). Elsewhere the presentation makes a reference to routing requests via Washington state which somehow converts them into court orders, not sure what that's about.
Also, the presentation tells agents to cover up the fact that it exists and how to do so, so we're back into "parallel reconstruction" terroritory.
That said, I actually care less about this sort of thing than what the NSA is doing, as it's (a) not classified and apparently can be learned about via the regular channels despite their requests for secrecy and (b) it's being used to catch more ordinary, every day criminals like people who rob jewellery shops or make bomb threats. The almost total blurring between corporation and state is very concerning because it implies there's nothing stopping it from stepping over the line and becoming used for petty political activism or worse, but at least they try to actually justify the programs existence with examples (unlike nearly all NSA training material, it seems).