The union says a long-term care home in Athabasca is violating rules that require a registered nurse to be on staff.
The union says the private, for-profit seniors centre run by Extendicare Canada has refused since last fall to hire registered nurses.
The presence of a nurse is one of the regulations that must be fulfilled for a facility to be legally defined as a nursing home.
The union says it was informed by a senior health official that Extendicare decided to use licensed practical nurses because of the difficulty in recruiting RNs.
Union president Heather Smith says the issue was raised with Health Minister Stephen Mandel in January, but there's been no response.
"It now appears (Alberta Health Services) and the government are prepared to ignore the government's own laws and regulations," Smith said in a statement released Tuesday.
"As a result, we believe we have no recourse but to seek relief from the courts in the form of an order to the government to enforce the Nursing Home Act and the Nursing Homes Operation Regulation."
The union asked Court of Queen's Bench on Monday to issue such an order in the case of the Athabasca nursing home.