What I want to know is, where did they get that "proof" that Moira slept with Merlyn?
That's funny. And a good question. Maybe the district attorney slipped into her Manhunter costume and found proof from 18-19 years ago to use in the trial.
Now that I rewatched it, it makes a bit more sense.
Merlyn would have had the paternity test done.... somehow. Presumably years ago, when Thea was born and he did the math, using his mad Ninja skills to get some of Thea's blood. He passed this on to the DA using his secret connection to the office.
His intent may have been twofold: To take revenge on Moira, and to put his heir in charge of Merlyn Global. We'll have to see about that.
The flaw here is, for the paternity test to stand up in court, there has to be proof that the test actually compared Thea's blood to Malcolm's. What I mean, it's not like Malcolm and Moira went into the clinic with Thea and everyone showed their ID.
All Moira really had to do was state that she had never consented to any test for Thea, this could not possibly be a real test, and where did the DA obtain this document? (Moira would be refusing admission.) The onus is now on the DA to prove the test is real, which he cannot do without revealing that Merlyn is alive.
I remember an episode last season where some dude O.D.ed shortly after leaving Ollie's night club and Lance suspected that Tommy and Ollie were involved in selling Vertigo. Lance subpoenaed their accounting books and LATER THAT SAME DAY, Lance's partner told him that they had found a thousand dollars missing from the books. That is one helluva forensic accountant working for Starling City to find a thousand dollar discrepancy after just a few hours of pouring over their books!
Yes, I remember that. I suppose we could give them a pass because the club had only been open a few weeks/months and there would be limited journal entries to go over.