The scoping exercise into illegal birth registrations is restricted to only examining records for specific markers which might indicate illegality.
A number of interim reports relating to the investigation show that the review is looking at a sample of just over 1% of records held by Tusla and the Adoption Authority of Ireland (AAI) and is not looking for evidence of illegal adoptions. Instead, records are being compared against a set list of 24 labels or "markers" which might indicate an illegal birth registration has occurred.
Adoption campaigners have repeatedly said that the review would be largely cosmetic in nature if it was confined to searching for markers rather than a forensic examination of records for all forms of illegal adoption.
They have also stressed that - as illegal registrations were usually carried out to circumvent adoption law - it is unlikely that adoption agencies signposted that fact using markers or labels in any systematic way.
Other forms of illegal adoption include cases of falsified or questionable consents, where the mother consenting was a minor; adoptions granted in the absence of birth certificates of any kind; and in the case of children whose parents were married and instances of correct birth registrations which resulted in illegal adoptions.
The scoping exercise was announced by children's minister Katherine Zappone last May following the discovery by Tusla of 126 cases in which births were illegally registered between 1946 and 1969 in the records of the former St Patrick’s Guild adoption agency. Some of these records were marked "adopted from birth". The records transferred to the agency in 2016.
The review is being led by independent reviewer, Marion Reynolds, and involves the AAI and Tusla.
The Department of Children and Youth Affairs (DCYA) had previously declined to reveal the sample size of the 150,000 records to be examined as part of the review or the methodology involved.
The interim reports of the independent reviewer, recently placed on the DCYA website, reveal that, of the 30,000 records held by the AAI, 4,351 across five adoption agencies were identified as "relevant to the review". A total of 459 were then examined for markers.
Of the 70,000 records held by Tusla, a total of 1,082 records are being examined across 20 adoption societies, six nursing homes and five regions where children were boarded out prior to adoption becoming legal in 1952.
In total, the review will examine just 1,541 or 1.5% of the more than 100,000 records held by Tusla and the AAI.
It has also emerged that the report is set to be delayed again - for the third time. Just days after Ms Zappone told the Dáil on March 28 she expected to receive the report before Easter, Ms Reynolds informed the DCYA on April 1 that the report would be available to the DCYA "for a factual accuracy check before the end of May 2019".
This date is dependant on the AAI and Tusla reports being completed by the end of April. Ms Zappone will receive the report after this check has been completed.
The final report was initially due in October of last year. However, in September Ms Zappone said the report had been delayed until mid-December due to it being a “very complex" task and issues that had arisen "in relation to data protection and GDPR”.