The suit, filed in state Circuit Court yesterday, alleges that new pill provisions make it impossible for shareholders of CB Bancshares to support the merger, call a special meeting or remove the pill by electing a new board that may favor the $270 million buyout offer.

Poison pills are common among publicly owned corporations, including Central Pacific, and generally make it more difficult for any one shareholder to gain control of a company.

The CB Bancshares pill allows shareholders to buy additional shares at a discount if 15 percent or more of company stock is acquired by someone, who is excluded from the discount and ends up owning fewer, less valuable shares.

But Central Pacific said in its suit that qualifying to release the CB Bancshares pill was broadened to include shareholders with at least 15 percent collective ownership if they “embark on a common purpose or act” even under an informal agreement.

Central Pacific said that could intimidate CB Bancshares shareholders from urging one another to support the acquisition or from calling a special board meeting.

“The (CB Bancshares) board has given itself a weapon to threaten shareholders who wish to support the Central Pacific bid … because such activity may result in their having triggered the new pill,” the suit said.

Central Pacific also said in the suit that CB Bancshares gave its existing board the power to keep the pill provisions even if shareholders elect a majority of new directors who want to undo the terms.

“With this amendment, the board is attempting to control the pill even after being voted out of office,” Central Pacific said in the suit.

The suit also challenges an amendment made last week to CB Bancshares bylaws that give the company up to 120 days to call a meeting after a shareholder request, saying that four months is unreasonably long.

CB Bancshares issued a statement today that said it had yet to receive a copy of the complaint for review, but that it believes the suit is without merit.

“We will do our utmost to defend our company and our shareholder rights plan,” CB Bancshares said, adding that the new provisions are generally more consistent with terms adopted by other public companies.

The legal challenge brings to four the number of lawsuits filed over the unsolicited offer, which management of both local banks initially contested largely through a public-relations campaign.

But after a key shareholder vote in May in which CB Bancshares blocked consideration of the offer, the battle for shareholder support has turned more to the courts.

Last week, CB Bancshares sued to suspend the voting rights of its shareholders who pledged to support the takeover. The company also is asking a court for the right to buy back the stock of its shareholders who gave Central Pacific voting power without proper approval, including shares acquired by Central Pacific.