Officially, the lawsuit has one plaintiff so far. Dianna Stanway is the representative plaintiff in the court action that first must be certified by the court as a class action, allowing the other women to join.
Stanway alleges she got breast cancer after taking Premarin.
The drug's maker, Wyeth-Ayerst International, asked the court to dismiss the legal action, saying the Canadian women didn't have jurisdiction to sue the American firm.
But Justice Miriam Gropper refused to release the international firm from responsibility.
"I find that the U.S. defendants' admitted engagement in activities in relation to the Canadian companies and to consumers in Canada is sufficient to establish a real and substantial connection,'' she said in a written ruling released Monday.
More from CTV.ca here