There might have been a time when a person could point the finger— at least in part, towards Google. That was back when Google did a poor job of notifying users that the images it displays, even when the users searches for free images, may be subject to copyright.
However, Google began displaying prominent warnings about possible copyright issues when ever it returned search results that included images. So, do not expect a court to be sympathetic to the idea that Google told you so.
Furthermore, courts have been very pro-copyright holder when it comes to assuming that an infringer should know that images generally require a license.
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