The gaping divide separating House Judiciary Committee members on the Stop Online Piracy Act was abundantly clear as a marathon markup of the measure got under way Thursday.

The dissension didn’t break down by party. Reps. Darrell Issa of California and Jim Sensenbrenner of Wisconsin were among the Republican committee members who criticized the anti-piracy bill championed by House Judiciary Committee Chairman Lamar Smith (R-Texas).

Several members from both parties — including Issa and Reps. Zoe Lofgren (D-Calif.) and Dan Lungren (R-Calif.) — argued that the bill was being pushed through too fast without input from technical experts on what it would mean for the structure of the Internet.

But Smith and Reps. Bob Goodlatte (R-Va.), John Conyers (D-Mich.) and Howard Berman (D-Calif.) said something needs to be done now to protect rights holders from sites that profit from offering illicit content and knockoff products.

In his opening statement, Smith argued that SOPA is needed because the Digital Millennium Copyright Act only provides limited relief for rights holders when it comes to rogue foreign sites.

For example, Smith said DMCA doesn’t protect trademark holders and consumers from sites that sell counterfeit goods such as knockoff pharmaceuticals. It also doesn’t address the problem that online pirates use ad services and payment processors to fund the sites, he said.

“Laws equip U.S. authorities and right holders to take action against criminals who operate within our borders,” Smith said. “But there is no parallel authority that permits effective action against criminals who operate from abroad.”

Ranking member Conyers, a co-sponsor of SOPA, noted that a broad swath of labor unions, businesses and academics also support the legislation. He questioned the motives of opponents.

“All we’re trying to do here is stop online piracy. Since when did opposition get so fierce against this? What could be behind the motives of people or organizations that don’t think stopping online piracy is something that we need to deal with?” Conyers said.

Lofgren said the bill would undermine the structure of the Internet, arguing that it would employ the kind of technical measures used by repressive governments to stifle free speech. It would “lead to a Balkanization of the Internet,” she said.

But Berman, whose district encompasses Hollywood, countered that there’s a big difference between enforcing intellectual property rights “and seeking to suppress political conduct, political speech and dissent.”

Sensenbrenner, meanwhile, warned that the domain name-related provisions would potentially confuse the Internet security protocol DNSSEC so it could “not tell the difference between sites that have been blocked by law enforcement and those that have been sabotaged by hackers.”

Issa said he worried about the “little guy” Web entrepreneur who could be put out of business if the Justice Department oversteps its bounds and wrongly goes after the domain name of his or her site when it’s actually legitimate.

“They’re going to be out of money,” he said. “They’re going to be destroyed.”

Supporters countered that the Justice Department would have to obtain a court order before a domain name could be taken down.

This article first appeared on POLITICO Pro at 2:16 p.m. on December 15, 2011.