The bill must now be re-approved in the assembly due to amendments made while in the Senate.
Dustin Sternbeck, a spokesman for the D.C. Metropolitan Police Department, said that the police do not believe that the protesters participated in "a First Amendment assembly".
The rules designated part of the steps as a "First Amendment assembly area" and placed limits on the size of signs and other objects allowed on the steps.
The largely Sandinista national assembly voted for the amendments for a second time on Tuesday as required for them to become law.
"A new bill, brought to the floor of the assembly, is open to amendments, it is open to persuasion," Mr O'Dowd said.
"My regret stems from my belief that this assembly has, in rejecting amendments brought forward at earlier stages of the bill, missed an opportunity, not only to reduce the negative impact that this legislation will have on so many of our citizens, and on society as a whole, but also an opportunity for this assembly to show that it is capable of challenging the shackles of parity," he said.
He successfully lobbied for inclusion of freedom of assembly in the First Amendment, and was a leading architect of the Fourth Amendment protections against search and seizure.
In 1994, the assembly approved a similar amendment.
But some commissioners at the assembly who opposed the amendment said they did not accept Mr. Anderson's prediction, and said recent Presbyterian history was on their side.
The increasingly influential national assembly approved a constitutional amendment that gives it the power to hold no-confidence votes and to dismiss government leaders, including the president and prime minsiter.
