PHOENIX — Candidates cannot automatically be held responsible when forged signatures turn up on their nominating petitions, even when they gathered the names themselves, the Arizona Supreme Court ruled on Tuesday.

In a decision with potential implications for future elections, the justices acknowledged there was evidence seven signatures on nominating petitions for state Senate candidate Toby Farmer had been forged. And Farmer himself had signed the back of the petitions saying he had personally collected and witnessed the signings.

But the justices said absent hard evidence the candidate actually knew the signatures were forged, courts will not presume that to be the case.

And that means they will not apply a state law that disqualifies candidates guilty of forgery from running for office for five years.

The justices, facing a deadline for printing primary ballots, had already issued a summary order last month allowing Farmer to remain on the ballot.

But what they left unsaid, until Tuesday, was exactly why they could not conclude forgeries are not presumed to be the work of petition circulators, including candidates, without more evidence.

The ruling does not disturb the ability to have forged signatures disqualified, but if a candidate still has enough valid signatures, they are not automatically removed from the ballot.

If a court concludes a candidate knew of any forged signatures, that person cannot run at all. But Tuesday’s ruling said judges cannot infer candidates know of forgeries. That puts the burden on challengers to prove otherwise.

Deputy Secretary of State Jim Drake said his office sees very little of this kind of activity by candidates themselves. Drake said forgeries are more likely to show up on things like initiative petitions where proponents may have to gather more than 300,000 signatures.

The case involves Farmer’s Republican primary challenge to oust incumbent Sen. Don Shooter of Yuma. Shooter responded with a lawsuit challenging Farmer’s nominating petitions.