When an eight-member federal jury retreats behind closed doors this week to decide the outcome of the latest Apple v. Samsung patent showdown, a phantom Silicon Valley behemoth lurking in the room will play a decisive role in the verdict.

With the four-week trial winding to a close, it has become crystal clear that this courtroom conflict has been about Mountain View-based Google as much as the irreconcilable feud between Apple and Samsung over the rights to smartphone and tablet technology.

Lawyers for Apple and Samsung will present their closing arguments on Monday or Tuesday with billions of dollars at stake -- and Google will no doubt be mentioned as often as iPhones and iPads.

FILE - This April 9 2014, file photo, shows the Google logo at a store in Hialeah, Fla.
FILE - This April 9 2014, file photo, shows the Google logo at a store in Hialeah, Fla. (Alan Diaz/AP Photo)

The reason? Unlike 2012's first trial between the two companies, Samsung this time invoked Google as its primary defense, flatly telling the jury that Apple's true legal beef is with Google and its Android operating system, which runs the nine Samsung smartphones and one Galaxy tablet targeted in Apple's patent lawsuit. In essence, Samsung says, this trial has the wrong defendant.

Although Apple has dismissed that defense, suggesting Samsung is trying to hide behind Google, legal experts say the jury may be more receptive to Samsung's position than in the first trial. A federal jury sided with Apple in that trial, involving an older line of products, and Samsung was hit with nearly $1 billion in damages.

But, trial observers say, Samsung bringing Google and its omnipresent Android system to the defense case may be a smart move with a Silicon Valley jury perhaps reluctant to find the search giant copied Apple. In a stark departure from the first trial, when no Google executives took the stand for Samsung, Google executives such as Hiroshi Lockheimer, vice president of engineering, this time vouched for the originality of Google technology in Samsung devices and repeatedly told the jury they never stole ideas from Apple.

In the first trial, Samsung could not as readily exploit the Google defense because the Apple patents generally dealt with the "look and feel" of Samsung-designed products. Google declined to comment on the current trial.

"The Apple-Samsung courtroom clashes have always been about messaging -- messaging for the jury and beyond," said Robin Feldman, a Hastings College of the Law professor. "In the first trial, Samsung struggled to craft a simple message that the jury could grab on to. The defense-by-proxy argument in this one could be easier for a jury to absorb."

Added Brian Love, a Santa Clara University law professor: "(Google executives') very presence suggested to the jury that Apple is picking on the wrong company. Google's involvement in the case seriously undermines Apple's narrative that Samsung is a blatant copier."

Nevertheless, experts also say Apple has presented another strong case, deluging the jury with powerful evidence that Samsung took to copying to keep pace with its rival. Apple attorneys showed the jury memos calling the iPhone threat "urgent" and declaring that "beating" Apple is the South Korean company's top priority.

Apple contends Samsung devices have violated five iPhone and iPad software patents such as those for the slide-to-unlock and auto-search features, hammering on the point that Samsung -- not Google -- controls the technology it sells and includes in its smartphones and tablets.

"Apple is right that if Samsung adopts the infringing technology, it is liable for doing so," said Mark Lemley, a Stanford University law professor. Apple dropped a bit of a bombshell as the trial's evidence phase wrapped up last week, introducing documents showing that Google is so intertwined with Samsung that it has agreed to cover part of the legal costs if the South Korean manufacturer loses to Apple. As a result, legal experts also say the jury could look at Apple's bid for $2.2 billion in damages with a view that it is reaching not only into Samsung's deep pockets, but also Google's, a company with a market capitalization of $395 billion.

The closing arguments this week are expected to recap this debate over whether Apple has a right to collect from Samsung if much of the software at issue -- in smartphones such as the Galaxy S3 -- is Google's doing.

In the end, when the jury returns its verdict, there is plenty of middle ground. Apple has asked for more than $2 billion; Samsung experts valued Apple's patent claims around $38 million.

John Quinn, Samsung's lead lawyer, told the jury at the trial's outset that "this is really about Apple vs. Google's Android." And Samsung has introduced internal Apple documents discussing the Android threat, including late Apple CEO Steve Jobs' declaration of a "holy war" against Google, which he considered a copier of Apple software.

But Apple's lawyers told the jury Samsung's argument is smoke and mirrors. That theme is expected to resurface in the closing arguments.

Samsung "crossed into the dark side of intentional copying," Apple lawyer Harold McElhinny said on the trial's first day.

Howard Mintz covers legal affairs. Contact him at 408-286-0236 or follow him at Twitter.com/hmintz