Women would be left to take the second stage of the medical abortion alone, with no medical oversight.
Dr Calderwood refused to withdraw the plans.
SPUC Scotland is launching a legal challenge against Scotland's top doctor over plans to allow women to take abortion drugs at home.
Deadline passed
Lawyers acting for the Society wrote to Dr Catherine Calderwood, Scotland's Chief Medical Officer, before Christmas, warning that unless the decision to authorise the taking of misoprostol (the second stage of a medical abortion) outside a clinical setting was reversed within three weeks, legal action would be taken.
However, in a reply to SPUC Scotland, Dr Calderwood has said: "We have noted the contents of your letter, but do not accept that there is any reason to withdraw the approval."
John Deighan, CEO of SPUC Scotland, has therefore officially launched the judicial review. "We have now formally instructed our legal team to prepare court papers to go before a judge and this will be done before January 25," he said.
Unlawful position
"The Scottish Government has made its decision to continue with this policy. We believe this is an unlawful position. They have refused to engage in discussion on the matter despite the detailed concerns we raised with them. Therefore, we have been left with no option but to proceed to challenge it through the courts.
Danger to women
"The abortion pill has been greatly pushed by the government as if it were some sanitised and easy way of ending a pregnancy," Mr Deighan continued. "It is far from that. The move to trivialise abortion is one that harms women and creates an environment where some women are even urged to have an abortion because it does not suit others.
"Our legal advice is clear, and we are confident that the Scottish Government’s decision to give women the abortion pill to take home is not in keeping with the law," he concluded.
Any court hearing is unlikely to take place for several weeks.
The story has been widely covered in the Scottish media, including on STV, The Herald Scotland, and The Evening Express.