She served as Deputy Secretary General of the Council of Europe from 2002 and retired from the post in 2012 and was succeeded by Gabriella Battaini-Dragoni.

[3] She was elected President of Missing Children Europe in 2013, a position she took over from former Advocate General at the European Court of Justice, Sir Francis Jacobs.

[Notes 2] On 2 November 2015, the Japanese Ministry of Foreign Affairs (MOFA) issued a complaint to the Office of the High Commissioner for Human Rights (OHCHR) over De Boer-Buquicchio's comment of 26 October, which they quoted as saying that 13% of schoolgirls were involved in enjo kōsai ("compensated dating"), and asked her to disclose the source for the claim of 13%.

[12][13] In response, the OHCHR released a clarification from the Special Rapporteur acknowledging that she had not received an official statistic concerning this matter while in Japan and explaining that the 13% figure was an estimate found in open sources that was mentioned – thanks to a mistranslation, as 30% – to highlight a phenomenon that must be urgently tackled.

[14][non-primary source needed] Following the issuing of a press release[15] by the Ministry of Foreign Affairs on 9 November in which it requested the withdrawal of the remark and that the report be based on objective data, she addressed on 10 November a letter to the Permanent Representative at the Permanent Mission of Japan to the United Nations in which she stated that she would not refer to this estimate in her Report to the UN Human Rights Council.