MANILA, Philippines (UPDATE) - Sen. Miriam Defensor Santiago on Tuesday walked out of a Senate plenary session after criticizing Senate President Juan Ponce Enrile and fellow senators who engaged in gutter talk during Monday's floor debates on the ethics case of Senator Manny Villar.

In an impassioned speech, Santiago reminded her fellow senators that the rules of the Senate frown on the use of improper language during debates in the plenary, especially against each other.

"Our language and behavior did not serve the nation...Our parliamentary immunity entitles us to freedom from liability in anything we say or do against anybody except our fellow senator or against any public institution such as the institution of the presidency, Congress or Supreme Court," she said.

Santiago reserved her harshest criticism for Enrile whom she took to task for implying that she had not brushed up on jurisprudence that showed that a senator could be censured by a vote of the majority.

She cited the Philippine Daily Inquirer account of the heated Senate session which said that "Enrile shrugged off Sen. Miriam Defensor-Santiago’s opinion that the penalty of censure would require the vote of two-thirds of the Senate membership."

The PDI article added: "Enrile countered that 'these so-called experts have not read the precedents in the country and the US.' In the United States, members of Congress could be censured by the vote of the majority, he said."

Santiago said Enrile's behavior was "unparliamentary," and urged all her colleagues to resign if they continue to behave in such a way.

The female senator insisted that the Senate Committee of the Whole report recommending Villar's censure would need two-thirds of the Senate or 16 votes to adopt the committee report.

Santiago was particularly incensed with Enrile since she had earlier opposed an alleged plot by Villar's allies to remove Enrile as Senate President.

Just difference of opinion

"Sinasabi ko na nga e, hindi na kailangan palitan ang Senate President dahil kakaunti na lang ang panahon na naiiwan pero insultuhin ba naman akong ganyan (I already said we don't need to replace the Senate President because time is too short and then I get insulted) ," she said.

She added: "I have always been polite in expressing a legal opinion contrary to those of my colleagues very conscious that our rules in the Senate provide that we can say or do anything against anybody except our fellow senators and except a public institution. But I will certainly not countenance any senator insulting me just because my opinion happens to be different from his."

Santiago said the debate on whether Villar could be censured by a majority or a two-thirds vote was an honest difference of opinion because there was a gray area in the law on how to censure mere disorderly behavior or heinous behavior of a senator.

She added that in the Villar case, the Senate should have proof beyond reasonable doubt of Villar's guilt before going as far as expelling the senator from its ranks.

"We should not expel a senator on mere credible, substantial evidence because that could be tantamount to capital penalty or punishment. If you expel a senator, isn't that killing him as well as a politician? Biro mo, senador ka pinatanggal ka ng kapwa mo sariling senador. Para na rin pinatay ka. Therefore, my argument is we should apply proof beyond reasonable doubt," she said.

While she was speaking, Enrile suddenly stood up and passed by the podium, appearing to be walking out of the session hall.

After her speech, Santiago walked out of the session hall.

"Eh kasi, nakakainis eh. Eh insultuhan nang insultuhan tungkol sa bagay na pulitika, at kakaunti nalang ang panahon namin... dapat kaming mag-resign kung ganyan lang kaming mag-aaway-away kami at wala naman na kaming silbi sa taumbayan. Eh bakit pa kami magdi-display ng aming bad manners and bad conduct?" Santiago told ABS-CBN News anchor Henry Omaga-Diaz just moments after she walked out of the Senate session hall.

Enrile, however, said that he did not walk out of the session - he just went to the comfort room.

"Nagpunta ako sa banyo dahil tumaas ang BP (blood pressure) ko kanina... kung akala niya ay siya ay nainsulto, ay open naman ang husgado na idemanda ako eh para doon na natin pag-usapan. Hindi 'yong murahan dito," Enrile said. With a report from Henry Omaga-Diaz, ABS-CBN News