Tim Cook will give evidence in the class action lawsuit, which alleges illegal hiring practices between Silicon Valley's major players.

Stretching back nearly 200 legal fillings, the case centres on accusations of no-hire "gentleman's agreements" between the top companies in the area, alleged to bring financial benefits across the firms.

With cases against Apple, Google, Intel, Pixar, Adobe, Intuit and Lucasfilm, the plaintiffs argue that the companies conspired to not compete for employees which subsequently ensured mobility was restricted and employee salaries remained low.

But after a year of little development, Judge Lucy Koh has ordered a four-hour deposition of the Apple CEO regarding the opposition of Apple's attorneys.

Reuters reports that Judge Koh says internal emails reveal executives suggest this could be true, meaning Cook will be called to speak during the case despite claiming to have nothing to do with any potential secret deals.

In 2010, it was reported that the Department of Justice ordered the companies to stop the practice, with the plaintiffs now seeking financial compensation nearly three years later.

If successful, attorneys representing the plaintiffs believe the damages could run into the "hundreds of millions of dollars", representing a serious problem for Silicon Valley's top tech companies.