Cody Duty / AP

Occupy Houston protesters lay in the exit ramp at the Port of Houston Authority on Dec. 12.

Seven Occupy protesters were indicted on felony charges by a grand jury in Houston on Tuesday, a spokeswoman for the district attorney's office says, in connection with their demonstration at the local port as part of a national day of action by the movement.

The decision comes nearly a week after a judge initially dismissed the charges, saying the protesters could not be charged with possessing or using a "criminal instrument" – a felony in Texas – for their use of PVC pipe.

The protesters -- three from Austin, four from Houston -- put their arms through the pipe and used latches on it to connect together, making their arrest more difficult but not preventing it, said one of their attorneys, Daphne Silverman, of the National Lawyer's Guild in Houston. Donna Hawkins, a spokeswoman for the District Attorney's Office, confirmed the indictment.

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"They are feeling, 'wow,' is the word. ... They're in a lot of shock. They were very happy with the justice's decision last week, they believed in her, they believed in the justice system," Silverman said. "These people ... are not criminals. These folks are out there attempting to make the country better for all of us."

Silverman, who noted that she believed the law had been wrongly applied by the prosecutor, said it's likely the protesters will be back in court in January to talk about the next step, such as negotiations or to go to trial. If convicted, they face up to two years in jail.

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Protester Dustin Phipps -- who is not one of the seven charged -- said it was a "strategic move" by local police to discourage others from participating in civil disobedience.

"We definitely plan on fighting it," said Phipps, 28, a pre-medical student at the University of Houston. "We're going to move forward ... with faith and determination because we understand we have the rights and the upper hand, and we're going to make sure justice is served."

The protesters had joined with other Occupy outfits across the country that were conducting port shutdowns on Dec. 12 to economically disrupt what they called "Wall Street on the waterfront.”

Arrests on felony arrests were occurring in other cities, such as Denver and New York. Civil rights lawyers have suggested the use of felony charges was another form of crackdown on the movement.

The Houston Police Department has used the "criminal instrument" against protesters on previous occasions, according to Attorney Randall Kallinen, who is representing one of the seven protesters. The charge usually does not hold up in court in such cases, but because it is a felony charge it has a chilling effect on would-be activists, he said.

"We’ve been seeing more of them (felony arrests), especially beginning of November," said Gideon Oliver of the lawyers guild in New York. The police and the district attorney’s office have discretion in determining the charges, "and so there are two sort of steps in the process where ... the police or the DA, if they conducted a reasonable investigation, I think, in a lot of these cases would realize that they’re overcharging."

Msnbc.com's Kari Huus contributed to this report.