Overall decisions on the criteria for entry to higher education are a matter of academic decision for each individual institution. The allocation of standard entry places on the basis of application through the CAO is solely on the basis that an applicant satisfies the academic entry requirements of a higher education institution for the course to which they are seeking entry.
In the interests of supporting increased access to higher education some institutions also operate systems of entry for persons from economically or socially disadvantaged sectors of society, such as school leavers from disadvantaged schools, mature students and students with disability. Such systems are also competitive and operate on the basis that an applicant satisfy the minimum academic entry requirements to a course, in tandem with an assessment of other prior achievements and the overall motivation and capacity of an applicant to succeed in meeting the academic demands of a particular programme.
Under the Equal Status Act 2000 higher education institutions are required not to discriminate in relation to the admission any person on the basis of gender, marital status, family status, sexual orientation, religion, age, disability, race or membership of the Traveller community. I am not aware of any specific issue in relation to the allocation of third level education places to persons who are on the methadone programme.