MANILA, Philippines—Without published rules, the Senate could not compel members of the Cabinet and other executive officials to face inquiries in aid of legislation and all its previous hearings could be regarded as "null and void," Malacañang said on Sunday.

Citing Tuesday’s Supreme Court decision on the petition of former socioeconomic planning secretary Romulo Neri, Executive Secretary Eduardo Ermita said members of the Cabinet and other executive officials could skip Senate’s inquiries from now on until the proper publication of Senate rules on inquiries.

He said the officials should be guided by the ruling that upheld Neri's right to invoke executive privilege and refuse to answer questions on his conversations with President Macapagal-Arroyo on the National Broadband Network (NBN) deal with China’s ZTE Corp.

The Supreme Court voted 9-6 to uphold Neri’s invocation of executive privilege on the NBN-ZTE deal and voted 10-5 in nullifying the Senate’s action to cite Neri in contempt and to order his arrest for skipping subsequent hearings and for refusing to answer questions on the President’s reaction after he told her of an alleged bribe offer for his support of the $329-million ZTE deal.

The high court reminded the Senate of the need to publish the rules of procedure enshrined in Section 21, Article VI of the Constitution.

Ermita said that it would be an “abuse of authority” for the Senate to summon executive officials to inquiries without published rules as stipulated by in the court ruling.

Asked if Cabinet members could ignore Senate subpoenas, Ermita said, "of course, they can invoke the ruling."

He said senators could always run to the court for relief.

Ermita cited the high ourt ruling in “Tañada versus Tuvera” and again in “Neri versus Senate” about the “constitutional infirmity of an inquiry conducted without published rules."

"The Cabinet will invoke the ruling. All along the Senate has been conducting their hearing but it turns out they have yet to publish their rules of procedures," said Ermita, “so it turns out all their hearings can be considered constitutionally infirm."

Ermita read a three-page opinion drafted by the Office of the Executive Secretary’s legal team which said all Senate inquiries could be considered "invalid" until the full publication of its rules of procedures.

"The rationale for publishing rules is to inform the public of rules, which may have an impact on his person, property or liberty. It is basically a requirement of due process," said Ermita, reading from the Palace opinion.

"Before one is declared in contempt, fairness dictates that the person is informed of the rules and the only way for the public to be informed of said rules is by publication," he said.

Ermita said this ruling meant that “all the proceedings of the 14th Congress in relation to the national broadband network hearing, as well as other hearings, are Constitutionally infirm. They are null and void."

Ermita took the Senate to task for issuing an arrest warrant against Neri.

He explained that based on the high tribunal’s ruling, “only the courts can issue a warrant of arrest.”

"If there is a warrant of arrest, then there should be preliminary investigation to determine probable cause. There is no such procedure in the Senate," he said.

The Senate announced earlier that it would file a motion for reconsideration on the high court’s decision, which critics said diluted the legislature’s constitutional mandate of checking on executive branch and ability to prevent presidential abuse.

Senate Minority leader Aquilino Pimentel Jr. questioned the high court decision on Senate rules for this current session, which included the power to cite anybody in contempt and to order arrests.

Pimentel said the rules had long been published in national newspapers and that there would be4 no need to republish them after the election of a new set of 12 senators.

The Senate was unlike the House of Representatives whose members got elected every three years, Pimentel said. He said the Senate was a continuing body. "The rules of the Senate continue for as long as the Senate is in place," said Pimentel.