What is the test for "express contradiction" between two separate laws on custody of a child?

In Constitutional Law of Canada it is said at pp. 103-4 and 111: The clearest case of inconsistency, which I call express contradiction, occurs when one law expressly contradicts the other. For laws which directly regulate conduct, an express contradiction occurs when it is impossible for a person to obey both laws; or, as Martland J. put it in Smith v. The Queen, 1960 CanLII 12 (SCC), [1960] S.C.R. 776, 800, "compliance with one law involves breach of the other". For laws which operate at one remove from human conduct, that is to say, which operate only indirectly upon human conduct, the test of possible compliance with both laws may not be appropriate. But an express contradiction will occur if one law says x and the other law says not-x. • • • • • Where two spouses are separated, and a court order made under federal law grants custody of their child to the wife, while a court order made under provincial law grants custody to the husband, another direct contradiction occurs. • • • • • Whether the laws are inconsistent or not depends not on their dominant purpose or aspect but upon whether they are compatible in operation.