I think it must hinge on whether or not the guy actually acted to cause the invitation, or whether this was an automatic google thing based on previous emails between the two accounts.
If it was simply an automatic "add these people from your past emails" notification, then it seems very unreasonable to hold him to account for it. Sounds like the defendant needs a witness from Google about how Google+ works - which will almost certainly be difficult to get!
I think it must hinge on whether or not the guy actually acted to cause the invitation, or whether this was an automatic google thing based on previous emails between the two accounts.
If it was simply an automatic "add these people from your past emails" notification, then it seems very unreasonable to hold him to account for it. Sounds like the defendant needs a witness from Google about how Google+ works - which will almost certainly be difficult to get!