The Pepco-Exelon deal is done. What can opponents do now?

The D.C. Public Service Commission has approved the $6.8 billion merger between Exelon Corp. and Pepco Holdings Inc. and the two companies completed the transaction just a few hours later.

So are we done here? Not quite.

Opponents of the deal have 30 days to ask the PSC for reconsideration, meaning they can appeal to the commission to change its mind and undo the merger.

It's unlikely the PSC would go that route, but it's also the first step needed to challenge the merger in court. Opponents would…