New York (CNN Business) An outspoken Philippine journalist who was briefly detained last week says the country's case against her is "ludicrous" and "unconstitutional."

Maria Ressa, the CEO of the news site Rappler and a vocal critic of Philippines President Rodrigo Duterte, spent a night in the custody of the Philippines National Bureau of Investigation last Wednesday after she was arrested in connection with a "cyber libel" charge against her website.

"I think it's definitely intimidation, for me to spend one night in detention," she told CNN's Brian Stelter on "Reliable Sources" on Sunday. "I came out of that night thinking this is now a travesty of justice."

The charges stem from an article that was written by Reynaldo Santos Jr . and published in 2012 by Rappler. The piece claimed that the chief justice of the Philippine supreme court was using a car linked to a businessman who had been accused of involvement with illegal drugs and human trafficking. The businessman, Wilfredo Keng, filed the complaint.

Ressa, who worked for CNN before she founded Rappler, was arrested the week after she and her website were indicted.

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