The purpose of the hearing ostensibly is to decide whether an Oracle damages expert should be excluded from the case, as Google has urged. The expert, a Boston University economics professor, has estimated that Google should pay Oracle billions of dollars in damages. Google says his methodology is flawed and filed a from trial.

While two legal experts said they doubt Google's motion will prevail, more interesting are the questions that Judge William Alsup has said he plans to ask at Thursday's hearing. One is in a court filing last month that it infringed Oracle's patents, something Alsup said "appears possible."

Lawyers for the two sides may also argue about whether the case should be stayed pending reexamination of the patents at issue. Oracle said in a court filing Wednesday that the trial, scheduled for Oct. 31, should go ahead. Google said waiting for the patent office's final rulings would narrow the focus of the case. Google also hinted for the first time that .

Oracle , saying its Android operating system violates seven Java-related patents that Oracle acquired when it bought Sun Microsystems. It's one of several legal challenges to Android that might for use of the software.

The expert opinion, from Boston University professor Iain Cockburn, has not been made public. Google has said Cockburn calculates its damages at an "extraordinarily broad" range of US$1.4 billion to $6.1 billion. Oracle says the figure is precisely $2.6 billion, mostly for what it claims Google would have had to pay Sun to license the patents legally.