New checks will be introduced to make sure all NHS doctors can speak English well enough to treat patients, the Government has announced.
It comes five years after David Gray, 70, was killed by a German doctor on his first out-of-hours shift in the UK.
Daniel Ubani accidentally gave the pensioner 10 times the recommended dose of the painkiller diamorphine.
The locum was struck off the medical register in the UK, but still practises in Germany, despite admitting death by negligence in a German court.
Mr Gray's son Stuart, 53, himself a GP, said: "What Ubani had done was try to register with Leeds PCT (Primary Care Trust).
"They'd made him sit an English language test to see if he was proficient. He failed that, so he decided to apply to another PCT, this being Cornwall.
"They didn't bother to test his English language skills, put him on the list, once he was on the list he can practise anywhere in the country and he then went to practise in Cambridgeshire where he killed my father."
Last year, research by Pulse magazine for GPs found that 792 EU doctors were on the so-called "performers lists" of 51 Primary Care Trusts, allowing them to work in the UK. Of those, 657 doctors, or 83%, hadn't had their English skills tested.
From April 1 there will be one national list which every GP will have to be on before treating patients. There will also be a legal duty to ensure those on it have good English.
Health minister Dr Dan Poulter said: "It's not something that should cause huge public alarm, but it's something that we do know from the case of Doctor Daniel Ubani, and other doctors, who are sometimes flown in to do short-term locums in the NHS from Europe, that it is something that has actually caused deaths in this country.
"That's completely unacceptable and that's why we're introducing language checking for all overseas doctors including those within the EU."
But Dr Gray, of Blakedown, Worcestershire, has his doubts. He said: "I'd like to know how they're going to police it.
"If they say it's going to be illegal for the doctor to work here if they can't communicate in English, well, it was illegal for Cornwall PCT to put Ubani on their list, and no one has been held to account for breaking the law there."
Niall Dickson, chief executive of the GMC, welcomed the Government's plans. "This is good news for patients," he said. "The Health Minister's announcement today will help strengthen patient safety across the UK.
"Our position is clear - patients must be confident that the doctor who treats them has the right communications skills to do the job.
"If doctors cannot speak English to a safe standard then the GMC must be able to protect patients by preventing them from practising in the UK."