Joseph Berger is a past chairman of the Toronto district of the Ontario Medical Association, and past president of the Ontario branch of the American Psychiatric Association. He was also affiliated with the National Association for Research and Therapy of Homosexuality, an organization formed specifically to "cure" people of being gay - although his bios scrub this fact and it's not certain if he is presently affiliated with the group. (He was a Scientific Advisory Committee member in 2006, and a speaker on behalf of NARTH in 2010.) While a scientific adviser, Berger garnered notice when he recommended bullying as a solution to gender-diverse youth (original now offline):

"I suggest, indeed, letting children who wish go to school in clothes of the opposite sex - but not counselling other children to not tease them or hurt their feelings. "On the contrary, don't interfere, and let the other children ridicule the child who has lost that clear boundary between play-acting at home and the reality needs of the outside world. "Maybe, in this way, the child will re-establish that necessary boundary."

At the request of Gwen Landolt of R.E.A.L. Women of Canada, he sent a submission to the Standing Committee on Justice and Human Rights (JUST) to oppose the trans human-rights Bill C-279. The Association for Reformed Political Action Canada, a Christian advocacy group, has now forwarded this submission to every sitting Member of Parliament in anticipation of the third reading of the bill.

Berger urged MPs to oppose C-279, because, according to him, trans people don't exist:

Scientifically, there is no such a thing. Therefore anyone who actually truly believes that notion, is by definition deluded, psychotic.

He then goes on to explain that what trans people experience is "just unhappiness," as if risking losing everything - family, spouses, children, employment, friends, assets - in order to make a whole life change is simply the path of least resistance for unhappy people.

He takes some special pains to assert that he is "speaking now about the scientific perspective - and not any political lobbying position that may be proposed by any group, medical or non-medical." So he's putting aside his role as a champion of ex-gay therapy, as he presents a scientific argument that contains absolutely zero authoritative citations. Ironically, he concludes thus:

As a psychiatrist, I see no reason for people who identify themselves in these ways to have any rights or privileges different from everyone else in Canada.

I say ironically, because that is not what the Canada Human Rights Act does. Despite Berger's often-repeated reference to C-279 as granting "some special allowances or attitudes or possibly even 'rights'," what it would actually do would be to assure that trans people can't be denied employment, housing, and access to services simply because of who they are. Which would put them on the same level as everyone else in Canada.