In 2010, the government announced it had sued several large tech companies, including Apple, Google, Intel, Adobe, Intuit, and Pixar over their hiring practices. The companies' top execs had agreed to not "cold call" competitors' most valuable workers in an attempt to recruit them. That illegally stifled competition and held down the salaries of skilled employees, the government said.

The tech companies quickly agreed to a settlement that brought the investigation and lawsuit to a close. However, a civil suit brought by five ex-employees followed, claiming that the former workers at Adobe, Intuit, and Intel lost out on better salaries because of the agreement. The lawsuit sought class action status. Earlier this year, US District Judge Lucy Koh, who's overseeing the case, said that Apple CEO Tim Cook should get ready to be deposed by lawyers representing the plaintiffs.

Today, the civil suit, which is against all six companies snared in the Department of Justice action as well as Lucasfilm, has hit a potentially fatal roadblock. This afternoon, Koh ruled [PDF] that the workers can't form a class, because their cases are too different to be lumped together as one.

If the litigation were to move forward, it could highlight some embarrassing e-mails from some of the nation's top executives at tech companies. That kind of evidence largely didn't come out from the settled government case. But there's a taste of it in today's order from Koh.

For example, Koh's order today quotes Pixar President Ed Catmull writing to Disney, saying "[w]e have avoided wars up here in Norther[n] Caliornia because all of the companies up here—Pixar, ILM [Lucasfilm], Dreamworks, and a couple smaller places—have conscientiously avoided raiding each other."

Koh took note of comments from Steve Jobs about recruiting as well: "When a recruiter from Google's engineering team contacted an Apple employee in 2007, Apple CEO Steve Jobs forwarded the message to Google CEO Eric Schmidt and stated, 'I would be very pleased if your recruiting department would stop doing this,'" Koh wrote in her order.

However, the judge also considered evidence from dueling economists: one representing the plaintiffs, who argued that "all or most" of the employees in the class had been harmed by the "no cold calling" agreements, and a defense expert who argued that any harm was individualized, not on a class-wide basis. She found flaws with the methods used by the workers' expert for showing harm and damages on a class-wide basis.

The plaintiffs will get another chance to make their argument, since Koh wrote the order "with leave to amend," which is not unusual when denying such motions on the first try. And they sound eager to do so. "Plaintiffs appreciate the court's thorough consideration of the evidence and are prepared to address the court's concerns fully in a renewed motion," a lawyer for the plaintiffs told The Associated Press.

Even though the tech companies won today, Koh seems quite convinced in places that the employees have a real case.

She was dismissive of some of the defense evidence, which consisted of employee declarations "drafted specifically to oppose this Motion." More convincing were the "internal, contemporaneous documents... such as CEO-to-CEO emails, Power Point presentations regarding compensation and recruitment... and inter-office communications."

Koh wants more evidence to be sure; and the plaintiffs will have a chance to give it to her. Koh writes:

"[T]he Court finds that Plaintiffs’ documentary evidence weighs heavily in favor of finding that common issues predominate over individual ones for the purpose of being able to prove antitrust impact. Nevertheless, the Court has concerns that Plaintiffs’ examples, though compelling, may not be sufficient to show that all or nearly all Class members were affected by the anti-solicitation agreements without additional documentary support or empirical analysis."

The evidence the workers' lawyers need may well be in their hands. Since the class certification hearing, they have deposed approximately 50 high-ranking employees at the defendant companies, including CEOs and heads of Human Resources. They've received 10,000 documents. There's a lot there, and some of the most interesting parts may finally see public scrutiny in the near future.