"Criticism of Israel is not anti-Semitic", says Professor Irwin Cotler, perhaps the world's foremost advocate for the rights and freedom of political prisoners.

The man who fought for the release of Natan Sharansky from the Soviet gulag was also legal counsel for Nelson Mandela during his incarceration, and has represented many political prisoners all over the world since then.

"Jews don't deserve special treatment because of the holocaust," he says in the breakfast lounge of the Johannesburg hotel where he's staying, glad to be back in the country for which he says has a special affinity.

"The last time I was here, a student at Wits University in Johannesburg asked me what I thought of Israel Apartheid Week.

"I replied that I have great respect for the struggle against apartheid here in South Africa. And it demeans this struggle to compare it to what is happening in Israel today.

"I'm not saying Israel shouldn't be held accountable for its actions. 

"But to compare Israel with South African apartheid shames the real anti-apartheid struggle.

"When people say there's apartheid in Israel, they're saying that in apartheid South Africa you had a free press, unqualified franchise, gay rights, and so forth. This is not true.

"The analogy is false and harmful.

"Recently the Canadian Parliament, of which I'm a member, passed a unanimous resolution condemning the global rising tide of antisemitism. 

"It included a section from the Ottawa Protocol, which says that criticism of Israel is not antisemitic, and that saying so is wrong. 

"But singling out Israel for selective opprobrium and condemnation, or denying Israel's right to exist and calling for its destruction, is discriminatory and hateful, and not saying so is destructive."

Cotler, who served as Canada's Minister of Justice between 2003 and 2006, first visited South Africa in 1981, at the height of what he refers to as the 15 minutes of fame he achieved for representing Sharansky.

"The day before I was to represent him in court I was arrested, detained and expelled by the Soviets. While being driven to the airport - I had no boarding pass - I spoke to the manager of the airline. 

"I asked him to tell the LA Times correspondent in Moscow, Dan Fisher, that I wouldn't be able to make it for dinner.

"That resulted in a front page headline of 'Sharansky's lawyer arrested and expelled'.

"So when I came here as a guest of the anti-apartheid movement, and met with several local lawyers fighting for human rights, such as Arthur Chaskalson, of course people wanted to hear about Sharansky.

"Soon, though, everyone wanted to know: why not speak about Nelson Mandela? 

"We arranged a big event, and after speaking of the Mandela's detention by the apartheid regime I was detained.

"I was told the foreign minister, Pik Botha, wanted to meet with me. As I walked into his office he asked me if I recognised the man in the photo on his wall. It was a photo of Sharansky. And he asks me: 'How can you, who defended Sharansky against our enemy, speak in the same breath of defending Nelson Mandela, our communist enemy? How?'

"I said that Sharansky and Mandela were fighting for the same thing. The USSR was a human rights violator, but South Africa was the only post-World War 2 government that instituted racism as a matter of law. 'Apartheid is a racist legal regime,' I said to him. 'So I will always fight it.'

"Botha said he should just expel me there and then, but because of my work for Sharansky, he'd give me 10 days to go around the country and see what was happening for myself.

"After 10 days I came back to him ansd said: 'You are right, it is a democratic country - if you're white. If you're coloured or black, it's worse than I thought'.

"I was asked by one of Mandela's lawyers, Issy Maisels, to help internationalise the struggle to free Mandela.

"I was asked to do for him what I had done for Sharansky. So that's how the two struggles, against Soviet oppression and apartheid, overlapped."

Cotler traces his passion for human rights advocacy back to his upbringing.

"My father taught me that the pursuit of justice is equal to all other commandments combined. 

"And my mother said: 'To pursue justice, you must feel the injustice around you."

Cotler believes that South Africa should be using the moral authority it has thanks to the struggle against apartheid to help political prisoners in other countries.

"Your country, thanks to its relations with various governments, is in a very good position to help several political prisoners.

"One is Iranian Shi'ite cleric Ayatollah Boroujerdi, who is in his ninth year of imprisonment. I was asked by his family to be his legal counsel. 

"He wants religious freedom in his country, an end to the persecution of minorities. He's been referred to as the Mandela of Iran. And as a result of campaigning for these things, he was convicted of insulting Islam.

"He hasn't been sentenced to die, but his family believes that withdrawing his medication, as the government is doing, is nothing else than a form of execution.

"Then there's Saudi Arabian blogger Raif Badawi, arrested in 2012 for running a liberal blog. In 2014 he was sentenced to 10 years in prison and 1 000 lashes, fifty lases a week. 

"His wife asked me to become involved in his case.

"In Venezuela, politician Leopoldo Lopez has been incarcerated by a government which has now, according to last week's Economist, gone from being authoritarian to a dictatorship.

"His detention is arbitrary and illegal. Even US President Barack Obama, who doesn't usually call for the release of political prisoners, has done so in this case.

"South Africa is a great friend of Venezuela, and its government may heed representations made by Pretoria. The same is true in the other two cases."

Cotler believes one of the keys to achieving the release of political prisoners is making governments realise that doing so is in their self-interest.

"I always wondered what role Gorbachev played in the release of Sharansky, so when I got the chance to speak to I asked him. He said while he was minister of agriculture he'd never heard of Sharansky. 

"The first time he heard his name was when he came to Canada to talk agriculture, but everyone just kept asking him questions about Sharansky. There were protests calling for his release.

"So when he became leader of the USSR, he called up Sharansky's file. 

"He said: 'I could see that. yes, he was a troublemaker. But a criminal? No. And keeping him in prison was costing us, politically and economically. It was in our self-interest to release him.'

"So in defending political prisoners we have to make governments understand this. This understanding is what led to success in both the USSR and South Africa.

"And look at the results today. One of the great legacies of Mandela was the establishment of the Constitutional Court, one of the great shining jewels of post-apartheid SA. 

"Your Bill of Rights is one of the best examples of such a bill anywhere. All this speaks to the importance of freeing political prisoners. Imagine what would have happened if Mandela hadn't been released?

"And Sharansky's release paved the way for the collapse of the Soviet Union. As a result so much of Eastern Europe has been democratised."

Unfortunately, Cotler's experiences in South Africa have not always been positive.

"I was here at a watershed moment for the anti-Israel BDS movement, at the 2001 world Conference Against Racism in Durban.

"When the conference was announced, I was very excited that a conference against racism, the first in the 21st Century, would be held in the home of the anti-apartheid struggle.

"But then I watched as a conference against racism turned into a conference of racism against Israel and the Jewish people.

"Fourteen years later this falsehood of Israel being an apartheid state has been spread for so long that more and more people are beginning to believe it. 

"I'm happy to say that my government, as the government of one of the leading nations in the struggle against apartheid, rejects this analogy.

"I really miss Mandela and his moral authority. He would never have called for the dismantling of Israel. He said that Israel has a right to exist. We need his wisdom in this debate. 

"For all its faults, Israel is the only democracy in the Middle East, with a free press, independent judiciary and functioning parliament. There are many other countries more deserving of critique.

"Israel is singled out for criticism, but there is silence about the oppression and human rights violations in in Saudi Arabia, Venezuela and Russia, and about Iranian apartheid.

"And that worries me deeply."

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