By Peter Brimelow Random House, 306 pages, $33.50 In Canada, immigration is usually portrayed as a left-right issue, with the left in favor and the right against. In fact, the political right is deeply split on this sensitive subject. That's why rightwinger Peter Brimelow finds himself attacking his ideological soulmates as he dissects American immigration policy in his book Alien Nation. Open, unselective immigration—the prevailing policy in both Canada and the U.S.—is a logical outgrowth of neoconservative ideology. Neoconservatives believe that market forces, not governments, should de...