Patents are governed by a specific jurisdictional statute that made this crazy.
The history is detailed well here: http://patentlyo.com/patent/2007/04/patent_jurisdic.html
THe TL;DR is:
It used to just be: Any civil action for patent infringement may be brought in the judicial district where the defendant resides, or where the defendant has committed acts of infringement and has a regular and established place of business. 28 USC 1400
Then in 1990, Congress added: For purposes of venue under this chapter, a defendant that is a corporation shall be deemed to reside in any judicial district in which it is subject to personal jurisdiction at the time the action is commenced. 28 USC 1391
This eviscerated the previous limitations.
Personal jurisdiction is a little tricky to explain in a single post, but suffice to say, for internet companies most likely the target of trolls, they will generally be found to be subject to personal jurisdiction everywhere in the US.
For example a lawyer looking to file a class action lawsuit often factors the venue that they will wind up in into their choice of a lead plaintiff.
But the notoriously corrupt patent appeals court -- the CAFC -- in its first decade of existence, abolished 28 USC §1400 by fiat.
The patent trolls went into business in East Texas soon after.
Normally, you pick the one that you live in, so that you don't have to travel. But for patents, many people pick East Texas, since they're more likely to get the verdict they want there.
Or perhaps better actually where your attorneys are located?
No. What you describe in the first sentence is basically what the old rule was, pre-1990 (28 USC 1400). The current rule is much worse (28 USC 1391).
Basically, you have the effect right, but the description of the pre-reqs wrong :)
The key difference is in whether or not you must have an established place of business for a suit to be brought against you in a jurisdiction.
Basically, the federal circuit's view of 28 USC 1391 is very different than 28 USC 1400.
If you look at cases prior to VE Holdings, they view 28 USC 1400, and in particular, the definition of "resides", very narrowly (to principal place of business/corp hq).
If you look at VE Holdings, and their view on 28 USC 1391, you can see it greatly expands the definition of "resides" to include essentially everywhere.