FUN FACT: According to the Canadian Association of Journalists, you don't have to protect a source if they lied to you- yet CBC won't reveal this source, I wonder why?? https://archive.is/bN0s5

Are there any cases in which it is acceptable or morally advisable to reveal a source?

In certain rare circumstances, yes. When journalists use confidential sources, their contract and their obligation is, as always, first and foremost to the public, not to the source. Revealing a source would be justified, for example, if a government source or agency leaked erroneous information – but only if they knew it to be wrong, not if they too were fooled or misled. Governments, police or other groups often leak information with the deliberate attempt to “spin” the news. If they have lied to you to get their version of the story out, they deserve to be exposed. That is why it is all the more important to check your sources and their motives.

RECOMMENDATION: If a source knowingly lies or hides an important part of the truth about a major issue or fact in the story, your obligation is to the truth, not the source. He or she has broken his contract with you and you can break your promise of confidentiality to the source.

My sister still believes the CBC is the best news outlet in thedworld. She's so smug about it too. It's hilarious.