Basically, some rules were established that allowed patent cases to be heard lightning fast in Texas' Eastern District and generally in favor of the plaintiff because the patent trolls knew these different rules for presenting arguments better than defendants did and abused the system.

"Ward’s rules unleashed what became known as the 'rocket docket.' In his first year on the bench, Ward heard 5 patent cases. In 2006 his docket had 87. 'I did not anticipate that there would be an explosion of lawsuits,' says the now-retired judge."

"Yet Marshall soon gained a reputation the judges may not have welcomed: it became known as a plaintiff’s playground, a place that frequently handed out tens, or even hundreds, of millions of dollars in damage awards. In 2006 the New York Times reported that of the patent cases that went to trial in Marshall, jurors ruled for plaintiffs 78 percent of the time, far more than the national average of 59 percent. From 2001 to 2006, plaintiffs prevailed in eighteen straight verdicts in Marshall."

http://www.texasmonthly.com/politics/patently-unfair/