The formal agreement bars "conduct that is prejudicial to the investigation."
Updated with NTSB statement below.
Tesla has withdrawn from the National Transportation Safety Board's "party agreement" related to the recent fatal Model X Autopilot accident.
The signed certification allows affected companies to be involved in an investigation into their products. Parties must agree to not release certain investigative information, however, before the NTSB concludes the inquiry.
Tesla promises to continue cooperating with the agency, providing technical assistance.
"Today, Tesla withdrew from the party agreement with the NTSB because it requires that we not release information about Autopilot to the public, a requirement which we believe fundamentally affects public safety negatively," the company said. "We believe in transparency, so an agreement that prevents public release of information for over a year is unacceptable."
To be clear, the party agreement does not have a blanket ban on publicizing information related to accidents. The NTSB investigator in charge (IIC) must approve any public statements, however, with a focus on releasing safety-relevant information without additional context that is "prejudicial" to the ongoing investigation.
"If necessary for public safety, and with the IIC's permission, party coordinators may release information to their respective organizations provided the information is factual, neutral and objective in tone, and without purported NTSB characterization of the matter's contribution to the underlying accident," the agreement says.
Tesla's statements have highlighted the need for drivers to keep their hands on the wheel and pay attention to the road at all times while Autopilot is engaged. The company has also argued that the victim in the Model X crash is solely responsible for the accident, with the damaged highway divider to blame for its severity -- not the Model X, which apparently steered itself into the concrete divider at highway speed.
Update: Contradicting Tesla's claim of a voluntary withdrawal from the agreement, the NTSB has fired back with its own statement saying the automaker violated the party agreement and was consequently dropped as a party involved in the official investigation.
"Such releases of incomplete information often lead to speculation and incorrect assumptions about the probable cause of a crash, which does a disservice to the investigative process and the traveling public," the agency said.