Royal Caribbean has claimed that the grandfather of Chloe Wiegand, who plunged to her death from the 11th deck of a cruise ship, was "unquestionably" aware that the window was open.
According to court documents, Royal Caribbean said security footage by on-board cameras showed Salvatore Anello held Chloe, who was 18-months-old, outside of the window for about 34 seconds before she fell.
The cruise liner believes Anello had to use "basic senses" to appreciate the danger of dangling his granddaughter out a window.
"There was no hidden danger - Anello knew the window was open," the cruise operator boldly states in court documents.
"His actions, which no reasonable person could have foreseen, were reckless and irresponsible and the sole reason why Chloe is no longer with her parents."
Anello has been charged with negligent homicide in his granddaughter's death in Puerto Rico, which prompted the Weigand family to counter-sue the cruise line as it failed to protect Chloe and other vacationers from potentially dangerous open windows.
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In the suit, the family claimed there was no signs alerting Anello that the window he lifted his granddaughter up to lean on could slide open.
Despite the ship's windows having handles and a blue-green tint, the suit claimed that Anello was colour blind and therefore could not tell a pane was missing.
Filing a motion to dismiss the Wiegands' case on, Royal Caribbean said it could no longer "limit its expressions to those of sympathy and support".
"After months of bearing false and inaccurate accusations, from the Wiegands' attorneys through the press, RCL now faces the legally mandated task of responding to a lawsuit the Wiegands' attorneys did not file in good faith," it said.
"This is not a case of an unknowing child approaching an open window and falling out because the window was defective or improperly positioned.
"Rather, this is a case about an adult man, Chloe's step-grandfather who, as surveillance footage unquestionably confirms: (1) walked up to a window he was aware was open; (2) leaned his upper body out the window for several seconds; (3) reached down and picked up Chloe; and (4) then held her by and out of the open window for thirty four seconds before he lost his grip and dropped Chloe out of the window."
Royal Caribbean denies breaching industry safety standards and claims the video along with the grandfather charged with negligent homicide as proof of his culpability.
"No facts are alleged that would show RCL knew or had reason to know there was any dangerous condition that would result in Chloe's death," the filing added.
"RCL owed no duty to warn Plaintiffs of the open and obvious danger associated with putting a child through an open window. Such reckless actions require no warning.
"Individuals merely need to use their basic senses to appreciate the obvious nature of the danger."
A federal judge is yet to rule on Royal Caribbean's motion to dismiss but a status conference is scheduled for March.
The Wiegands, from South Bend, Indiana, could claim unlimited damages for pain and mental suffering if their suit succeeds.