What happens if they claim they downloaded it from somewhere else that didn't include the license.txt file? There is no proof they ever were even notified of the license. (this is why we usually have people sign contracts)
Adobe is about 34 years old, so the copyright on any program that interacts with an Adobe file format (e.g. postscript, pdf) cannot have expired yet (in the absence of time travel). So if the source code did not come with a license, it is their responsibility to obtain one, or they can't use it.
> “Upon discovering Hancom’s abuse of the GNU GPL and infringement of Artifex’s valuable copyright in Ghostscript, Artifex demanded that Hancom cease its infringement and remit to Artifex a reasonable royalty for Hancom’s years of unlicensed use of Ghostscript,” the company said in its complaint. “Rebuffed by Hancom, Artifex turns to this Court to enjoin Hancom from further infringement and to seek relief and recovery for Hancom’s abuse of Artifex’s open source license.”
So the suit was filed only after Artifex had notified Hancom of the license and attempted to work out a solution out of court. There's no way to argue they didn't know about the license beyond a certain date, and it sounds like they willfully continued to infringe upon the license after said date.
If they used code that they downloaded without a license, they have violated copyright law. (All code created in the US and most other countries has a copyright at creation.)
So they either accepted the GPL or violated copyright.
