Pope Francis said on Monday that government officials have a "human right" to refuse to issue marriage licenses to homosexuals if they feel it violates their conscience. Speaking to reporters as he returned home from his 10-day trip to the United States and Cuba, the pontiff delved into some of the United States' thorniest political debates.

On the flight back to Rome, he was asked if he supported individuals, including government officials, who refuse to abide by some laws, such as issuing marriage licenses to gays.

"Conscientious objection must enter into every juridical structure because it is a right," Francis said. "I can't have in mind all cases that can exist about conscientious objection but, yes, I can say that conscientious objection is a right that is a part of every human right," he said, speaking in Italian.

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"And if someone does not allow others to be a conscientious objector, he denies a right," Francis said, adding that conscientious objection had to be respected in legal structures. "Otherwise we would end up in a situation where we select what is a right, saying: 'This right has merit, this one does not.'"

Earlier this month a city official in the U.S. state of Kentucky, Kim Davis, went to jail because she refused to issue a marriage license to a gay couple following a Supreme Court decision to make homosexual marriage legal. Davis's case has taken on national significance in the 2016 presidential campaign, with one Republican contender, Mike Huckabee, holding rallies in favor of Davis, an Apostolic Christian who has joined the Republicans.

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A reporter said the pope had become a "star" in the United States following his visit to Washington, New York and Philadelphia, and asked if this was good for the Church.

"The media uses this term, but there is another truth - how many stars have we seen go out and fall. It is a fleeting thing. Instead being a 'servant of the servants of God' does not pass," the pope said, referring to one of the titles of his office.