The gay or trans panic defence, also known as the Portsmouth Defence, is where someone claims that they were temporarily not responsible for their actions due to extreme shock. The shock results from discovering that someone is gay or transgender, or some action related to those factors such as a straight person being invited to participate in a homosexual relationship.
I know of at least once incidence in the US where a transgender woman was murdered after her sexual partners discovered she was not a cis woman. Has the gay/trans panic defence ever been successfully used to avoid conviction or to significantly lessen punishment?
I'm interested in all jurisdictions, not just the US. I believe that the name "Portsmouth Defence" comes from the city of Portsmouth in the UK, for example.