Hello and thank you for your question.
The canons related to participation in the eucharist may be found here http://www.vatican.va/archive/ENG1104/_P39.HTM
Canon 912 specifically states "Any baptized person not prohibited by law can and must be admitted to holy communion."
Canon 923 states "The Christian faithful can participate in the eucharistic sacrifice and receive holy communion in any Catholic rite, without prejudice to the prescript of can. 844."
Canon 844 may be found here http://www.vatican.va/archive/ENG1104/_P2T.HTM
In particular Canon 844(4) states " If the danger
or if, in the judgment of the diocesan bishop or conference of bishops, some other grave necessity urges it, Catholic ministers administer these same sacraments licitly also to other Christians not having full communion with the Catholic Church, who cannot approach a minister of there own community and who seek such on their own accord, provided that they manifest Catholic faith in respect to these sacraments and are properly disposed."
The US Conference of Catholic Bishops has issued a directive relative to Non-Catholics and Holy Communion which allows participation in communion by Non-Catholics with permission. The directive can be found here http://old.usccb.org/liturgy/q&a/mass/communion.shtml
I hope the above is useful to your discussion on this important issue. Please feel free to ask any follow-up questions.