BP has lost a bid to remove Patrick Juneau, the court-appointed administrator managing payouts to businesses and individuals seeking damages arising from the 2010 Gulf of Mexico oil disaster.
US District Judge Carl Barbier in New Orleans rejected several arguments by the London-based oil giant to oust Juneau, reports said.
The ruling is a fresh setback to BP's effort to limit costs from the April 2010 disaster aboard the Deepwater Horizon drilling rig that killed 11 workers and sent more than four million barrels of oil into the sea.
BP spokesman Geoff Morrell said the company "strongly disagrees" with Barbier's decision and could appeal.
In a four-page order, Judge Barbier said it was "beyond cavil" that BP knew of Juneau's prior consulting work for Louisiana. The judge also said BP's arguments were "mostly a regurgitation of old issues or complaints".
As to the only "new" issue, processing claims of individuals represented by the Plaintiffs' Steering Committee, Barbier said Juneau had the discretion to review claims out of order, and there was no evidence he acted improperly.
Morell said in a statement: "Simply put, it is unacceptable for the claims programme to continue operating as it has been - inefficiently, secretively, and marred by corruption, fraud, and conflicts of interest."
As of 10 November, about $4.24bn (£2.7bn, €3.4bn) had been paid out to 52,577 claimants, according to Juneau's claims website.
In October, BP estimated that its settlement with the PSC would cost $9.7bn, but that this amount could go "significantly higher".
The ruling follows BP's September motion, where it asked the US court to sack Juneau for failing to disclose a conflict of interest before taking up the job of handling damage claims from the 2010 Gulf of Mexico oil spill.
The motion said Juneau lacked neutrality because he had advocated for claimants even before being appointed to manage the settlement programme.
The 2 September motion was the latest in a series of legal challenges filed by the British firm, which has complained that Juneau has been too generous when approving claims.
The case is In re: Oil Spill by the Oil Rig "Deepwater Horizon" in the Gulf of Mexico, on April 20, 2010, US District Court, Eastern District of Louisiana, No. 10-md-02179.