> That's the how, not the why. They had a choice to do it this way.

I don't think it was that simple, considering that the Nortel portfolio covers a wide array of different technology areas and industries. What other feasible choice did they have? Transfer the patents to themselves? Six companies were involved, each infringing different subsets of the portfolio: who gets what patents? Even if they did divvy up the portfolio somehow, they certainly weren't going to keep them lying around, not after paying so much for them -- They had to be licensed. Splitting the portfolio would not only make it weaker, but it would mean multiple individual licensing efforts. Rockstar currently fulfills the same function that MPEG-LA does.

> And "operate autonomously" doesn't mean much when you first fill the subsidiary with nothing but litigators and patents that have already been licensed to everyone meaningful other than the parent's competitors.

If you read the document linked in the comment I cited, no, those patents were not licensed to anybody meaningful until the auction. But licensing efforts were on the way years when they were still owned by Nortel and before Rockstar was created, so pretty much everybody knew what was coming. That is why all these companies, including Google, were bidding for these patents in the billions.

> It's like setting loose a rabid animal near your competitor's business and then trying to disclaim responsibility because the animal was "operating autonomously." What did they expect to happen?

Well, they paid billions for these patents. Is it fair to them that other infringers get away scott free?

> Lawsuits against Google's customers instead of Google.

Google makes pretty much no money directly from Android. This inherently makes it difficult to extract damages from them. Not to mention that since Google bought Motorola, they do have lawsuits directly against Google as well.

> Suppose Apple files a suit against an Android manufacturer, then a year into the litigation they show up and say "oh hi, we just bought some new patents, so let's throw out all the work we did getting to this point in the trial and start over." That clearly stinks of harassment...

That's not how patent lawsuits work. Dozens or hundreds of patents are involved in a portfolio, but it's not feasible to sue over more than a handful of them, because court resources are extremely limited. If you see how past patent lawsuits have progressed, companies assert a small bunch of patents and over time winnow them down to an even smaller number that are mostly likely to prevail. It's actually rare to see new patents being asserted partway through a lawsuit because, as you said, it annoys judges -- typically a whole new lawsuit is filed instead, which is a whole lot of extra work.

This is intrinsically unfair to the patent-owners with large portfolios, because no matter how many patents are being infringed, they only get to assert a few, and even if they prevail, damages are limited to the patents asserted. This is why companies try to get injunctions -- that is the only way to get enough leverage to properly license an entire portfolio.

Multiple lawsuits seem like harassment only if you disregard the flip side of the coin, which is widespread infringement.

> By filing the litigation through Rockstar, they get a separate trial with two bites at the apple in front of two juries, the litigation costs more for the target because they have to defend two overlapping cases in different courts instead of having them consolidated, and they can do it again and again with different troll subsidiaries until their smaller competitors are destroyed.

If different patents and/or different products are involved, the cases are not overlapping, so it's not the same apple that they're getting bites at.