The Duke of Edinburgh will face no further action after a car crash near Sandringham last month, the Crown Prosecution Service has said.
Prince Philip, 97, voluntarily surrendered his driving licence on Saturday.
He has apologised for his part in an accident on the Sandringham estate in Norfolk on 17 January, when his Land Rover Freelander collided with a Kia carrying two women and a baby.
The driver of the Kia, 28, suffered cuts to her knee while the passenger, a 46-year-old woman, sustained a broken wrist.
Both required hospital treatment but a nine-month-old baby boy was uninjured.
In a statement, Chris Long, chief crown prosecutor for CPS East of England, said it would "not be in the public interest to prosecute" Prince Philip.
He added: "The CPS has carefully reviewed material submitted by the police in relation to a traffic collision on the A149 on 17 January this year.
"We took into account all of the circumstances in this case, including the level of culpability, the age of the driver and the surrender of the driving licence.
"We have decided that it would not be in the public interest to prosecute.
"All those involved in the collision have been informed and provided with a full explanation in writing."
The decision was made after considering evidence submitted by police and in accordance with the two-stage test in the Code for Crown Prosecutors.
A Buckingham Palace spokeswoman said: "The Duke of Edinburgh respects the decision taken by the Crown Prosecution Service."
Both drivers were breath tested and both provided negative readings, a statement from Norfolk Police said.
It added that written statements from both drivers were provided along with witnesses to the crash.
Officers also carried out an eyesight test on Prince Philip on 19 January, which he passed successfully.
Two days after the crash, Prince Philip was pictured driving without a seatbelt.