The DA in Kwazulu-Natal has written to Health Minister Manto Tshabalala-Msimang requesting that she formally intervene to protect Colin Pfaff, a doctor at the Manguzi Hospital in northern Zululand.
Pfaff was last week charged with misconduct for dispensing dual therapy treatment to HIV-positive babies.
The charges were brought by the KwaZulu-Natal department of health.
DA spokesman Mike Waters said the charges against Pfaff were "patently absurd" because on January 25, the National Aids Council approved a policy of dual therapy and that Deputy President Phumzile Mlambo Ngcuka had indicated that provinces were free to implement the new policy.
Waters said the hospital had procured its own funding for this treatment and was not in any way placing a financial burden on the state.
"The minister needs to do this not only for the sake of the doctor, who has been treated unjustly, and for the sake of babies who are now being denied a life-saving treatment, but also to demonstrate that she is actually committed to this policy," he said.
"Monotherapy" - to prevent the transmission of HIV to newborn babies - is now completely outdated, but South Africa "continues to have it as our official policy" - four years after dual therapy became the internationally-recognised best practice, he said.
"I believe it would be appropriate for the minister to intervene in this matter, not only to protect the doctor, who was acting in the best interests of his patients, but also to unequivocally demonstrate that she is committed to this policy - a commitment that the long delays in implementation have led many to suggest, is lacking," Waters said.