Some doctors have been prescribing medicinal marijuana for some time. But, until now, they didn't have any proof it actually worked. But now, a new study shows it can, in fact, alleviate some pain. So we want to know whether more medical proof will change Canadians' attitude toward pot.

Former baseball pitcher Roger Clemens pleaded not guilty to charges of lying to Congress today. He rejects claims he used steroids and human growth hormone. We'll look at what Clemens' claims of innocence say about him, baseball, and efforts to rid the game of performance-enhancing drugs.

Mark's away this week. Erica Johnson of CBC's Marketplace is filling in. And tonight, that show is launching a social media campaign as it begins a Big Gym Ripoff Search. We'll tell you how you can take part, plus we'll look at how more and more consumers are using social media to take big companies to task.

Join us at 8 p.m. ET. Live.