This was a "non-arm's length transfer" case. These rules in ITA s. 160 and ETA s. 325 allow CRA to collect money from spouses (or other non-arm's length parties, like shareholders) where a tax debtor transfers property to the non-arm's length party at less than fair value. The idea is that the tax debtor has given up property which would otherwise have been available for the tax debts. (Similar rules apply under bankruptcy laws and some provincial laws.) Relying on these rules, CRA can collect from the spouse at any time; there is no limitation period.
In this case, the spouse, Mrs. Strachan, said that when she bought shares from the corporation at less than fair market value, her husband hadn't transferred anything to her. Chief Justice Rip did not agree with her. (She also claimed that she got other shares from her husband before he had a tax debt. The TCC did not believe her or her husband on that claim either.)
See Strachan v. The Queen, (2013 TCC Rip CJ)