A Sanderson order requires not only that it was reasonable for the plaintiff to sue the successful defendant, but also that the unsuccessful defendant's conduct made it fair to impose costs liability. An unsuccessful defendant's conduct in amending its defence to implicate a co-defendant, without misleading the plaintiff or concealing information, does not satisfy this requirement. There is no obligation on a defendant to alert the plaintiff to the potential liability of other parties.
The full text is available to signed-in members, including the 4 later cases that cite this judgment.
1 of the 4 citing cases carry a classified treatment. How each court treated it is available to signed-in members.