Juan Carlos, 85, who abdicated in 2014.
A UK judge on Friday ruled that the former lover of Spain's former king Juan Carlos I cannot bring a claim of harassment against him in the courts in London.
"The High Court of England and Wales lacks jurisdiction to try this claim," judge Rowena Collins Rice said in a written judgment on the civil claim brought by Corinna zu Sayn-Wittgenstein-Sayn.
"I was shown no authority coming anywhere near supporting an assumption of English jurisdiction over a foreign-domiciled defendant in such circumstances," she added.
At the same time, "she has not sufficiently established that the 'harmful even' of which she complains -- harassment by the defendant -- happened in England", the judge ruled.
Danish businesswoman zu Sayn-Wittgenstein-Sayn, who is in her late 50s and lives in England, sued Juan Carlos, 85, who abdicated in 2014, and wanted damages for personal injury.
She alleged that he caused her "great mental pain" by spying on and harassing her.
Responding to Friday's ruling, Zu Sayn-Wittgenstein-Sayn said she was "deeply disappointed" and that it was "disheartening to see that victims of harassment often struggle to find justice in our legal system".
She added, "Juan Carlos has deployed his full armoury to grind me down and the reach of his power is immense.
"I am considering all options," she added.
Juan Carlos, who is married, was in an "intimate romantic relationship" with the divorcee from 2004 to 2009 and showered her with gifts, according to previous court submissions.
Zu Sayn-Wittgenstein-Sayn alleged that Juan Carlos began harassing her after their relationship broke down, using threats, break-ins at her properties and surveillance.
Three appeal judges in London in December ruled his ex-lover could not sue him for harassment in the English courts for the period while he was on the throne as he had immunity as sovereign.
But they left open the possibility that she could pursue him for his alleged behaviour after his abdication.
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