The Canadian Afghan detainee issue concerns Government of Canada or the Canadian Forces (CF) knowledge of abusive treatment of detainees in Afghanistan. The abuse occurred after Afghans were detained by Canadian Forces, and subsequently transferred to the Afghan National Army (ANA) or the Afghan National Directorate of Security (NDS) during the War in Afghanistan. The issue has sparked heated debate since Article 12 of the Third Geneva Convention (of which Canada is a signatory) states that "the Detaining Power [Canada] is responsible for the treatment given [to prisoners of war]". If the allegations of torture are true it would mean Canada is guilty of war crimes.

The allegations were first sparked by University of Ottawa law professor Amir Attaran, who claimed that full versions of government documents proved Canada had willful knowledge that torture would occur before handing detainees to Afghan authorities. Subsequent to this, two official complaints have led to official investigations and hearings by the Military Police Complaints Commission (MPCC). One of these unveiled parliamentary testimony by diplomat Richard Colvin, who claimed that many detainees were probably tortured, and it was a standard operating procedure for Afghan interrogators. The allegations have led to a showdown in the House of Commons of Canada, as opposition Members of Parliament (MPs) had called for the releasing of relevant documents in full and unredacted form, claiming parliamentary privilege to see them. The government maintained that they had a duty to protect Canadian soldiers and citizens as the documents contained sensitive information.

At the request of the Speaker of the House of Commons of Canada, a panel of former justices and selected MPs was tasked with sorting through the documents, and determining the need to release or withhold them. To date, only about 4,000 out of the estimated 40,000 documents have been released, A final report released in June 2012 found no wrongdoing by Canadian Forces members, but did issue recommendations related to improving military policing and MPCC access to information and witnesses. The Canadian public generally held views that there was knowledge of detainee abuse by military or government officials. The issue has also led to scrutiny on detainee treatment by other Canadian departments and the armed forces of other nations.

Canada's military involvement in Afghanistan began in 2002 with the International Security Assistance Force (ISAF), a coalition of soldiers from 42 countries, which was tasked as a counterinsurgency effort in response to the 11 September attacks. ISAF had initially been established as a stabilization force by the United Nations Security Council on 20 December 2001, to secure Kabul. The Canadian Liberal government at the time, under Prime Minister Jean Chrétien, chose to have the Canadian Forces (CF) hand over its prisoners to the United States, who led the fight against al-Qaeda and other insurgents. After NATO took command of Afghanistan in 2003, Abu Ghraib torture and prisoner abuse at the hands of the United States armed forces in Iraq came to the attention of the public, and Canada soon faced pressure to hand their prisoners to someone else. Canada entered into an agreement with the Afghan government and started transferring detainees to Afghan security forces, which comprised the Afghan National Army (ANA) and the Afghan National Directorate of Security (NDS).

On 18 December 2005, then-Chief of Defence Staff Rick Hillier signed an agreement between Canada's Department of National Defence and the Government of Afghanistan. The agreement did not include any explicit right of access by Canada to Afghan detainees. Members of the opposition requested then-Minister of National Defence Gordon O'Connor to renegotiate the prisoner transfer agreement. This request was dismissed, with O'Connor saying the International Committee of the Red Cross and the Red Crescent fulfilled the duty of ensuring fair treatment of detainees and Canada could be notified and take action in any cases of abuse. However, the Red Cross stated that their mandate was being misunderstood, and it was the responsibility of Canada. It maintained that it had no role in monitoring the Canada-Afghanistan detainee-transfer agreement, and that following long-established operating procedure, the Red Cross would not reveal to any foreign government any abuses it might find in Afghan prisons. While maintaining that detainee monitoring was the Red Cross's duty until March 2007, O'Connor apologized to the House of Commons for previously misleading them on the issue. In turn, a new agreement was reached in April 2007 that allowed Canadian officials to have access to Kandahar jails.

The first allegations of detainee abuse came in early February 2007, when University of Ottawa law professor Amir Attaran produced documents he had received through an access-to-information request showing that three prisoners in the custody of Canadian military police were brought in by their Afghan interrogator for treatment of similar injuries to the head and upper body, all on the same day. Attaran argued this could be evidence of torture on the part of the interrogator and should be investigated. Attaran has maintained these allegations, stating in 2010 that the documents show torture of detainees was an actual tactic used to obtain information during interrogation.

In April 2007, The Globe and Mail published interviews with 30 men who claimed they were "beaten, starved, frozen and choked after they were handed over to Afghanistan's National Directorate of Security" by CF members. It also revealed that it had received a censored report by the Canadian government on human rights in Afghanistan through an access to information request, and it contained "negative references to acts such as torture, abuse, and extra judicial killings [that] were blacked out without an explanation". This prompted intensive questioning in the House, to which O'Connor claimed that a new agreement had been reached, saying "we have, in the last few days, entered into a local agreement in the Kandahar province to enter the detention facilities any time we want". This would be reaffirmed by prime minister Stephen Harper, stating that there was "no evidence that access is blocked to the prisons", and that Afghan authorities had agreed to "formalize that agreement so there is no potential misunderstanding". Regardless, NATO secretary general Jaap de Hoop Scheffer announced that the Afghan government was to launch an inquiry about the fate of detainees. In January 2008, it was revealed that the government ceased the detainee transfers after an internal investigation revealed allegations of a detainee being abused on 5 November 2007.

Allegations regarding the treatment of Afghan detainees resurfaced in November 2009 via parliamentary testimony by Richard Colvin, the second highest-ranked member of Canada's diplomatic service in Afghanistan from 2006 to 2007. Colvin claimed that many detainees were probably tortured, and it was a standard operating procedure for Afghan interrogators. This was consistent with special reports by the United Nations Human Rights Commission and the US Department of State. Colvin also said the torture involved beatings, whipping with power cables, the use of electricity, knives, open flames and rape. The Canadian government dismissed opposition calls for a public inquiry the next day. "There has not been a single, solitary proven allegation of abuse involving a transferred Taliban prisoner by Canadian forces", Defence Minister Peter MacKay said in the House of Commons, with his parliamentary secretary suggesting Colvin was not credible.