A surprise AFL ruling has opened up the path for Geelong to secure Zach Tuohy from Carlton after the Cats were given unexpected permission to trade another first-round draft pick.

Geelong will give up their first-round pick next year as well as other draft picks this year and get Tuohy and draft picks back from Carlton in the deal.

The deal, if it goes through, will mean Geelong will not have had a first-round pick in three successive drafts.

The surprise move to be able to trade a future first-round pick was given AFL approval after clubs - including Geelong - believed they were precluded from trading another future first-round pick given they had last year traded out of this year's first round.