It was the US strategist Karl Rove who came up with a phrase: "When you are explaining you are losing." Sinn Féin leader Gerry Adams wrote a very long online article last weekend that illustrated that phenomenon well. It purported to put into context how the republican movement in the North had dealt with crimes, including sexual crimes, and how it had meted out justice.

However the article reinforced the reality that the allegations made by Maíria Cahill have widened to a potentially damaging debate for Sinn Féin and the IRA about its response to crime (especially sexual crime) in its own strongholds.

This is the latest instance of where a (female) victim of a very serious sexual assault (where the perpetrator was involved in Sinn Féin or the IRA) has met Adams and later reported a very unsatisfactory outcome from the meeting.

Áine Tyrrell, who was abused by her father, Liam Adams, a brother of Gerry Adams, contended that at times at their meetings in 1987, the Sinn Féin leader portrayed "our Liam" as a victim as much as herself.

In a potentially very damaging allegation, Cahill has asserted that Adams told her that some abusers could manipulate victims into thinking they enjoyed it. She said she replied she had not enjoyed the abuse. Adams has categorically denied the accounts of both women.

In relation to the Cahill case, Adams said last week that he asked Cahill's grand-uncle Joe Cahill to speak to her about reporting the incident to the RUC in 2000. Sinn Féin did not begin engaging with the police service until 2006, some six years later.

In 1995, Adams told supporters in north Belfast that they should not report incidents such as child abuse to the RUC. “The RUC are not acceptable and are indeed using these issues for their own militaristic ends.”

The RUC also had its own agenda at times. When Tyrrell’s mother went to the RUC in 1987 with the allegations against Liam Adams, its main interest was in recruiting her as an informer, not dealing with the abuse.

The other comment made by Adams which stuck out in recent days was his assertion that neither he nor Maíria Cahill discussed the details of her case when they met. Her cutting – and to some ears, credible – response was to ask if people thought they were talking about the weather.

In his online article, Adams tried to widen the issue into a societal one, where all institutions failed to grapple with the issue. He also argued the conflict and violence in the North had given rise to a deep suspicion and mistrust of state institutions by nationalist communities who turned to a reluctant IRA to fulfil the policing and justice duties.

"These actions were of their time and reflected not only a community at war but also an attitude within Ireland which did not then understand or know as we now do, how deeply embedded abuse is in our society."

On one hand, Adams is criticising the shortcomings of other institutions, but he also employs the standard defence of the Catholic Church when confronted with its own past – that these "actions were of their time".

Sinn Féin TD Mary Lou McDonald has called for anybody involved in covering up sexual abuse within the church to be prosecuted. The corollary is that that must also apply to Sinn Féin, but of course it is denying that there is any cover-up, which has echoes of the standard “mental reservation” response of the church.

Adams does admit the IRA was singularly ill-equipped to deal with the issue.

Another unsettling sentence is his almost throwaway remark: “The IRA on occasion shot alleged sex offenders or expelled them.” That opens up the Pandora’s box of punishment shootings and summary executions.

In 1992, an IRA gang forced its way into the home of John Collett in the Shantallow area of Derry and shot the 37-year-old with a .38 magnum, leaving him to die in a pool of his own blood. He was accused of abusing a large number of children.

The author Eamonn McCann wrote shortly after the killing: “The satisfaction of so many at the maiming and death reflects the cumulative brutalising effect of almost a quarter century of violence has had on all of us here.”

This came straight out of Lord of the Flies. It seems on occasion the IRA shot alleged sex offenders; on occasion, it expelled them. There is also some anecdotal evidence that, on occasion, it did nothing at all, especially if the perpetrator was well connected within the republican movement.

It is impossible to know because none of this happened in an open way. The response seemed to be hugely varied and wildly inconsistent, with some being killed and others getting away without any punishment.

In his blog, Adams said that he and Martin McGuinness had publicly commented against punishment beatings from the mid-1980s. In the early 1990s the international human rights organisation Helsinki Watch came to the North to investigate punishment beatings. They reported that at least 1,670 had taken place between 1969 and 1992, the majority, 1,061, in nationalist areas.

From 1988 to 1991, after Adams and McGuinness spoke out, they continued apace, with some 400 carried out. Unsurprisingly, Helsinki Watch was highly critical of a set-up in which the IRA was the investigator, prosecutor, judge, jury and executioner – rudimentary justice and rudimentary injustice in simultaneous motion.