Press covering the trial have been referring to a "secret agreement" between the two which was hatched in 2012.
The pact between Google and Samsung was "revealed" in a videotaped deposition played to the eight-person jury hearing Apple's patent infringement case against the Korean firm, in which the iPhone maker is seeking more than $2 billion in damages.
This means that Google would assume responsibility for Samsung's defence if Apple brought claims against the company over those patents.
The patents in question were US 6,847,959 and 8,086,604, which related to the Android search box, and US patent 7,761,414, which related to the Gmail app.
Apple lawyers just wanted to show that Google and Samsung had been working together to defend against those patents and that they should ignore claims because they related to software developed by Google.
Press reports muttered about how Google lawyers looked uncomfortable appearing in court and the implication was that they had been caught out. Bloomberg said that Apple's presentation of a "Mobile Application Distribution Agreement" between Google and Samsung, was intended to show the jury that Samsung hasn't been forthcoming about Google's behind-the-scenes role.
This is important because the case between Apple and Samsung has always been a proxy war between Google and Apple. Jobs' Mob never took Google on directly but instead tried to put the frighteners on suppliers and especially its number one competition Samsung.
Samsung's lawyer characterised the case in his opening argument as "an attack on Android" and has used Google engineers to prove Samsung didn't need to copy Apple to equip its phones with newish technology.
Samsung would cheerfully have paid Apple off ages ago, but it seems that the company wants funny money for patents which are only a small part of the phone itself. Apple is seeking $2.19 billion in damages while Samsung is asking the jury to award $6.2 million.