Federal constitutions have usually been written by politician-legislators. Practical deficiencies can arise when there are modern problems which were not anticipated by the authors, there is overlap between the interests of the central and subsidiary governments, the wording of responsibilities is lacking sufficient detail, or the distribution of federal and state rights and responsibilities is inappropriate or unworkable. Clear and detailed responsibility for environmental protection and management is a frequent example of inadequacy in most federal constitutions. Another common feature is for a federal government to reserve for itself areas of jurisdiction where it will be shown there is a substantive national interest. In interpreting this, public officers have a tendency either to err into broad interpretation and intrude into states' interests, or to claim no interest, leaving the area uncovered by any jurisdiction. In cases of disputed claims, it is necessary to resort to judicial review.
Under the Canadian constitution, the national interest in fish is as a natural resource; its interest in rivers includes navigable rivers. The legally-defined provincial interest in fish is as an economic reserve; it also is responsible for any non-federal matters to do with rivers. The following situation develops: Loggers upstream go to a provincial minister of British Columbia to get a permit to float logs down a river. This is appropriate because the river concerned is not classified as a navigable river, and permission is given. During the transportation, however, the federal government intervenes, saying that logs damage the spawning grounds of salmon, which as a natural resource is under its care. So the Queen in right of Canada has the option to take to court the Queen in right of British Columbia, the province. To circumvent lengthy legal proceedings, a political solution was for the provincial government to impound the Queen's property (the confiscated logs), convey it most expediently into safe storage by floating it under government supervision downstream, pay the fines for its recovery, and recoup this from the loggers as their permit fees. And what of the interests of the salmon ?
Federalism is not a political ideology as much as it is a wisdom applied to politics. However, its present use is closer to horse trading with large doses of expediency and the philosophy of "divide and rule".