leges posteriores priores contrarias abrogant
So no, killing a Basque person would have been legally no different than killing anyone else.
There was also a law on the books until 1991 that you could legally kill Turks on sight, due to an incident that didn't even involve Turkish people to begin with[2] (Icelanders at the time apparently didn't differentiate them from Algerians).
It was repealed, but not due to any legal practicality. The Turkish national team refused to travel to Iceland unless the law was repealed, so it was struck from the books as a purely symbolic gesture.
At the time, Algeria was under the rule of the Ottoman Empire
Seems the original Vikings were afraid of being Viking'd themselves and put into Law?
>"The decision to do away with the decree was more symbolic than anything else," Westfjords district commissioner Jonas Gudmundsson told reporters last month. "We have laws, of course, and killing anyone — including Basques — is forbidden these days."