BP has released an internal investigation into the Deepwater Horizon rig disaster, which led to the release of five million barrels of oil into the Gulf of Mexico. The report and accompanying video basically blames everyone for the disaster, from misreadings of well integrity tests before the explosion, to the failure of the blowout preventer, to flawed design of various other prevention systems.

The executive summary and the full investigation rely heavily on jargon, but they basically describe a systemic failure. However, BP cleverly sidesteps the question of well design, for which they have personal responsibility, and basically looks at the incidents on the Deepwater Horizon in a vacuum, as the New York Times reports.

The report, which took about four months to complete, focuses less on decisions that BP made in designing and drilling the well than on what rig workers, mostly from Transocean, did after the blowout occurred.

“To put it simply, there was a bad cement job and a failure of the shoe track barrier at the bottom of the well, which let hydrocarbons from the reservoir into the production casing,” BP’s departing chief executive, Tony Hayward, said in a statement on Wednesday. “Based on the report, it would appear unlikely that the well design contributed to the incident, as the investigation found that the hydrocarbons flowed up the production casing through the bottom of the well.”

While it puts some responsibility on BP for errors made — such as misreading pressure data that indicated a blowout was imminent — the report tries to undermine the notion that the company acted with gross negligence.

The key to this for BP is to ensure the blame for that failure gets spread wide. Because financial liability for the company is at stake. Transocean, for example, immediately responded to the report by calling it “self-serving”:

“This is a self-serving report that attempts to conceal the critical factor that set the stage for the Macondo incident: BP’s fatally flawed well design,” according to an e-mailed statement from a company spokesman. “In both its design and construction, BP made a series of cost-saving decisions that increased risk — in some cases, severely.”

According to Transocean, this included neglecting to run a cement bond log, which documents an evaluation of the integrity of cement work performed on an oil well, and failing to conduct a complete “bottoms up” circulation of the well to ensure the quality of the cement seal.

BP in its report points the finger at both Transocean and Halliburton, which the company contracted to do the cement work.

Almost from the moment of the explosion on the rig, we’ve seen this circular firing squad of finger-pointing, with each major company involved in the drilling operation singling out the others for blame. It’s in the financial interest of each company to do so. If Transocean can prove that BP acted with gross negligence in the design of the well, they essentially get off the hook for all the liability costs. And BP wants to draw them in. The companies are playing out in the court of public opinion what eventually will get decided by a court of law.