With the killing of protestors this past Sunday, we are seeing the last days of the regime of the mullahs in Iran. The regime has been repressing violently those dissidents who protest the apparent rigging of the June 2009 presidential election. Each day of protest the dissent meets with more brutal repression, radicalizing more people, engaging more sectors of society.

Police are starting to walk away from the repression. As the dissent broadens and deepens, the police and army will see their friends, their neighbours, their relatives on the other side. They will abandon repression in increasing numbers. The repression will collapse and the regime will end.

Should outsiders do anything? There is reason to hesitate.

• The regime blames outsiders for creating and manipulating the dissent. The more vociferous outsiders are the more ammunition outsiders give to the regime in its campaign to blame its foreign enemies for the dissent.

• The leader of the dissent, Mir-Hossein Mousavi, the presidential candidate from whom victory seems to have been stolen, was prime minister of Iran from 1981 to 1989. During that period, the regime as a whole and he personally were complicit in gross human rights violations, including mass killings, inflicted on the Iranian people.

One of Mousavi's key supporters is Akbar Hashemi Rafsanjani, president of Iran from 1989 to 1997. Buenos Aires prosecutors have charged Rafsanjani with ordering Hezbollah to carry out the July 1994 bomb attack on the Argentine Jewish Community Centre (AMIA) which killed 85 people and injured hundreds.

• The current regime has stated it is determined to proceed to nuclearization and appears hell bent on weaponization. On this issue, as alarming as the statements and behaviour of President Mahmoud Ahmadinejad have been, Mousavi has been worse. When he was prime minister of Iran, he was knee deep in the secret development of Iranian nuclear capacity, authorizing the purchase of centrifuges on the black market.

Ahmadinejad in November 2009 backed away from a deal his negotiators had accepted to ship Iran's uranium outside for enrichment and return as fuel rods for civilian reactors, a deal which would have prevented the weaponization of Iran's uranium. One reason for Ahmadinejad's equivocation was the opposition of Mousavi to the deal. Mousavi has historically and consistently taken the position that uranium enrichment must be done inside Iran.

• We have seen all this before. The Iranian revolution of January 1979 was sparked by protests against human rights violations of the regime of the Shah of Iran. The current regime rode to power on the wave of protests of those human rights violations. Yet, the successors to the Shah inflicted human rights violations on the people of Iran far worse, far more systematic, than those inflicted by the regime of the Shah. The mere fact that an opposition protests human rights violations inflicted on its supporters is no guarantee that it will come anywhere near to respecting human rights when and if it achieves power.

• There is a direct link between the leader of the opposition in Iran and the mass killing of the lead opposition force outside of Iran. Outside of Iran, the largest, the best organized, the most persistent voice for a democratic Iran is the National Council for Resistance in Iran (PMOI).

One component of the NCRI is the People's Mojahedin of Iran (PMOI) or Mujahadeen e Khalq (MEK). The PMOI (but not the NCRI) has been classified as a terrorist organization by the US and Canada. It was recently delisted as terrorist by the European Union after court judgements finding that there was no evidentiary basis for the listing.

Yet, the PMOI and the NCRI are both banned in Iran. A group of PMOI refugees from Iran living in Camp Ashraf in Iraq have been victims of brutal repression by Iraq at the behest of the Iranian regime.

The connection between the Mousavi supporters within Iran and the NCRI outside of Iran is nil. Some 30,000 political prisoners, primarily PMOI, were massacred while in prison, starting July 1988, during the time Mousavi was prime minister. It was protests by Ayatollah Montazeri against these killings which led to his dismissal as successor to Ayatollah Khomeini.

• The disputes within Iran between the government and opposition often revolve around the true meaning of Islam. The most recent killing of protestors this past Sunday was awful by any standard. Yet, within Iran it is condemned as a violation of the holiday of Ashura, which commemorates the death of Shiite Islam martyr Imam Hussein. It is inappropriate for non-Muslims to say what is and what is not Islam. When it comes to respect for human rights, this sort of debate should be an irrelevancy.

Despite all these reasons for hesitancy, my view is that we who are outside should join with those who are inside in combating the stealing of the elections and the repression of the protestors. This is not an issue of insiders or outsiders, Iranians or foreigners. The crimes of the regime are crimes against humanity. They are crimes against us all. We have every right to protest because we too are the victims.

We should certainly be aware that the people whose direct victimization we are protesting have, in many cases, been themselves knee deep in human rights violations. Yet, human rights do not belong just to the good. They belong to everyone, to the worst scoundrels, simply because of our common humanity.

Human rights are not a reward bestowed on those who behave in the right way. A mass killer is as entitled to have his basic human rights respected as a saint.

What the content of those rights is varies from case to case. In the case of Mousavi and Rafsanjani, the rights to which they are entitled are the rights associated with a fair trial for crimes against humanity. Nonetheless, we should not abandon our commitment to human rights even when we are called on to honour the rights of those who themselves have flouted respect for human rights in a flagrant way.

Today I stand before a group organized by the NCRI combating human rights violations in Iran, protesting the brutal repression of the supporters of Mousavi last Sunday. Many of you have close relatives who were murdered by Mousavi and his colleagues in 1988. You protest human rights violations even though the direct victims of these violations support those who are the murderers of your families.

I congratulate you for that. That is how it should be. That is what human rights should mean. I only hope that someday in Iran those in power show the same sensitivity to human rights values that you are showing here today.

David Matas is an international human rights lawyer based in Winnipeg, Manitoba, Canada.