Yes, of course.
Special advocates are intended to enhance the fairness of a closed hearing process concerning secret evidence without compromising Canada's ability to safeguard security information. They protect fairness for the party that is excluded from the closed hearing, as well as the public's right to free expression, by ensuring that any secrecy in the court proceedings is necessarily justified.
You can have special advocates either challenging the amount of secrecy that the government is seeking with respect to the evidence, or testing with due diligence and adversarial submissions the sufficiency, weight and appropriateness of the evidence that the government seeks to rely on. There's a very long history in the courts of using special advocates to protect the openness of the courts as well as the fairness of those proceedings.