* Not disclosing HIV to partners can be sexual assault
* Court clarifies "significant risk" standard
* Those with low HIV level using condoms don't have to tell
Oct 5 (Reuters) - Canada's top court said on Friday that failing to tell a sexual partner you have HIV is only sexual assault if there is "a realistic possibility" of transmitting the virus that causes AIDS.
In a unanimous decision, the Supreme Court of Canada rejected the government's argument that everyone who has HIV should be required to disclose that condition to all sexual partners in any circumstance.
Several groups involved in the case, including the Canadian HIV/AIDS Legal Network and the Canadian AIDS Society, took issue with the court's standard of a "realistic possibility", saying it is too severe, and calling the decision "a major step backwards for public health and human rights".
The HIV groups said in a release that the risk of spreading HIV is made negligible just by using condoms, and that the court's decision "blatantly ignores solid science".
In 1998, the court found that not telling a partner about one's HIV status was a form of aggravated sexual assault if there was "significant risk of bodily harm". On Friday, the court clarified what might constitute a significant risk.
It said someone with a low viral load who uses a condom has not put their partner at significant risk. Viral load measures the severity of HIV infection, and some treatments reduce the level, making transmission less likely.
The court noted that standards might change in future cases since its decision does not preclude the law from "adapting to future advances in treatment" or risk factors it had not directly considered.
It said that risk of transmission, rather than actual transmission, is not a crime in many other countries, and that this "sounds a note of caution against extending the criminal law beyond its appropriate reach in this complex and emerging area of law".
Forcing everyone to disclose their HIV status would risk sending people who have no put anyone at risk to prison, the court said.