The facts were:
1. There was a notice on the outside of the box saying that use of the product was subject to an EULA. Zeidenberg was not bound by that.
2. Zeidenberg opened the box, opened the CD case, put the CD in the drive and ran the software installer on the CD, which presented him with the full EULA and the opportunity to agree to it, or the opportunity to cancel and return the software for a refund. He clicked "Agree" to that.
It was the clicking "Agree" after having a chance to review the EULA that bound him to it, not opening the packaging.
Also, if he was not offered the opportunity to disagree and return the software, it would not be binding.
It's unlikely it will ever be legal to claiming someone's actions before they've been presented the full license text count as assent to said license.
It is, however, possible to patent genetic modifications in the UK (and the EU), and for the duration of the patent, require anyone growing plants produced from those modifications to buy a (compulsary) license from you.
https://en.wikipedia.org/wiki/Directive_on_the_legal_protect...