Legal action has been launched in Los Angeles by Harry and Meghan after drones were allegedly used to take pictures of their 14-month-old son Archie.
A complaint filed at the Los Angeles County Superior Court on Thursday claims an unnamed individual photographed Archie at their home during lockdown.
The couple are claiming the pictures were an invasion of privacy.
The lawsuit highlights privacy laws in California.
Prince Harry and Meghan are now based in Los Angeles, having stepped back as senior royals at the end of March.
The couple's lawyer, Michael Kump, said: "Every individual and family member in California is guaranteed by law the right to privacy in their home. No drones, helicopters or telephoto lenses can take away that right.
"The Duke and Duchess of Sussex are filing this lawsuit to protect their young son's right to privacy in their home without intrusion by photographers, and to uncover and stop those who seek to profit from these illegal actions."
Harry and Meghan are constantly tracked by paparazzi, the lawsuit alleges, who have tracked them down to their home in Los Angeles, flying helicopters overheard and cutting holes in their security fences.
