By Isabel Ordonez Of DOW JONES NEWSWIRES HOUSTON (Dow Jones)--Investors in Anadarko Petroleum Corp. (APC) seem to be confident about the independent oil and gas producer's bid to limit liability stemming from the Deepwater Horizon oil spill by proving that the company's partner, BP PLC (BP, BP.LN), the operator of the broken well, was intentionally reckless. But legal experts said the path to show that BP acted with willful carelessness when drilling the deepwater Macondo well, which has been gushing oil more than two months, isn't easy. At stake is Anadarko's share of economic damages and containment and clean-up costs associated with the spill. BP so far has spent more than $2 billion in the response effort and has set aside $20 billion for damages; Anadarko, which owns 25% of Macondo, could be liable for a quarter of that amount. Shares of Anadarko were recently trading 1.9% down to $42.62, after closing Monday 2% up to $43.42. Shares of the Houston-based Anadarko were reacting to a statement the company released Friday saying the massive leak was caused by BP's "reckless decisions and actions." On Monday, Anadarko filed with the Securities and Exchange Commission a copy of its contract with BP, in which it highlighted a clause that allegedly exonerates Anadarko and fellow minority partner Japan's Mitsui & Co. (8031.TO) from their share of the cost of damages in case of "gross negligence and willful misconduct" in the part of BP and also from any punitive damages. BP rejected Anadarko's claims over the weekend. BP Chief Executive Tony Hayward said in an statement that other parties besides BP may be responsible for costs and liabilities arising from the oil spill. "We expect those parties to live up to their obligations," he said. BP declined to comment further for this story. Anadarko's move to blame BP eased some of the concerns raised after credit rating Moody's downgraded Anadarko on Friday to the first notch in the "junk" range. "The possibility that Anadarko may not be liable for costs related to the incident strengthens the case for investors to buy Anadarko today," Barclays Capital analyst Thomas Driscoll wrote in a note to clients. But to prove that BP exhibited gross negligence, Anadarko must show that "BP knew the risk and they made a conscious decision to proceed," said Richard LaGarde, a Houston-based arbitration attorney. Gross negligence has been hard to prove in the past because courts have been conservative and strict in their requirements of evidence, LaGarde said. If Anadarko files an arbitration claim, it could take months or even more than a year to obtain a resolution. Therefore, it wouldn't be surprising if Anadarko and BP reach an agreement before going to the arbitration process in order to avoid lengthy legal ordeal, said Harry Stansbury, a New-Orleans based attorney. The contract between BP and its Macondo partners stipulates that the parties must resolve disputes involving more than $500,000 through an arbitration process. Before initiating an arbitration claim, the well owners have about 80 days to try to resolve disputes in good faith negotiations. Anadarko spokesman John Christiansen said Monday the company's statement was an attempt to state its position regarding BP's liability on the spill, but added that Anadarko is not necessarily planning to file a lawsuit or an arbitration claim against BP. "We are still evaluating our contractual remedies," Christiansen said. Anadarko also received last week a bill from BP on costs associated with the leak. Anadarko said it is still reviewing the bill. Analysts from UBS, however, are bracing for a protracted legal battle, saying that Anadarko's move "clearly sets the stage for Anadarko's future legal actions against BP." UBS suggested that Anadarko would try to prove BP's gross negligence by using some of the decisions noted in a June 14 letter written by House Energy and Commerce Committee Chairman Henry Waxman (D., Calif.) and Rep. Bart Stupak (D., Mich.) to BP's CEO. According to the letter, investigators found that BP took shortcuts in the well design, cementing and drilling mud efforts and the installation of key safety devices in an effort to avoid losing money. Responding to questions from U.S. lawmakers in a hearing last week about some of those decisions, BP CEO Hayward said the design used on the Macondo well was not unusual. Hayward also said that BP, Transocean, Mitsui and Anadarko have been named by the U.S. government as being "responsible" for the disaster. Current estimates for total cleanup, compensation and penalties for the Gulf's oil spill are between $20 billion and $140 billion spread over a period ranging between five and 20 years, said Fadel Gheit, an analyst with Oppenheimer & Co. "We think Anadarko would benefit from reducing its total financial exposure to less than $10 billion, either through negotiation or legal action" against BP, Gheit said. -By Isabel Ordonez, Dow Jones Newswires; 713-547-9207; isabel.ordonez@dowjones.com (END) Dow Jones Newswires June 22, 2010 11:29 ET (15:29 GMT)