Probably not in real life but this is a soap!
Possibly some of Callum's family will crawl out of the woodwork to support him, and do we know the extent of Callum's police record? According to
this wiki page, he's only been to prison once for assaulting a judge. Given that was years ago, and if he's not been charged with anything since (despite being a known drug dealer), a good lawyer may be able to paint him as a more reputable figure than he actually is. Also, there's David's own sordid past to consider.