President Michael D Higgins has said that no one should receive special treatment when it comes to justice issues in Northern Ireland's past.
He was responding to a question about the arrest of Sinn Féin leader Gerry Adams at an economic luncheon in Chicago.
The President also questioned the economic policies of the European Central Bank.
Billed as the keynote address of his trip to the Midwestern United States, President Higgins spoke about economics, ethics and environmental responsibility to the renowned Chicago Council on Global Affairs.
President Higgins was asked from the floor about the arrest of Mr Adams.
Although he would not comment specifically on the case, he said when it came to resolving justice issues of the past that treatment could not be selective between the State and individuals or between one sub-institution of the State and different groupings of individuals.
He said that when it came to dealing with the past, it was adjusting it to the present that required the justice.
President Higgins also said we could not be selective when it came to "reaching back" into the past.
The President said there were many complex issues, such as who was called a victim.
He said it was a "real problem" in how to deal with the past, and that there had been collective killings on both sides.
He said he believed those involved do need assistance from "outside" in dealing with it.
He was also critical of those in the banking and economic fields, calling the European Central Bank's interest rate policy 'strange".
He said that if the Central Bank claimed that maintaining low interest rates would lead to reduced unemployment, then as an academic he wanted to see the proof of it.
He also said that those who had advocated light touch regulation had "much to answer for".