In the mid-1990s in the United States, several courts were asked to decide whether wolves were illegal immigrants. Ranching groups that were against the proposed reintroduction of the wild animals to Idaho, Wyoming and Montana were trying to block their transport across the border from Canada. The appeal failed and the foreign wolves were delivered and released.

In recent decades, many more in the legal profession have become familiar with Canis lupus. The grey wolf, and its place in the US landscape, sharply divides opinion — both scientific and political. Broadly speaking, conservationists want the wolf population to expand into its historical range, whereas the ranching community is anxious about large numbers of a top predator roaming free. Both sides can point to scientific research and ecological opinion to support their stance.

The battle over the fate of the grey wolf is gearing up for a new conflict, perhaps the most significant yet. As we report on page 143, the US Fish and Wildlife Service (FWS) has extended the period for which it will allow public comment on its controversial proposal to strip the grey wolf of its federal protection. The agency wants to remove the animal from the list of those protected under the 1973 Endangered Species Act, and to hand responsibility for its management and conservation to individual states. The FWS claims that the move follows the “successful recovery” of the wolf in two key regions. Scratch the surface, though, and it looks more like a cost-cutting exercise and, to some, a politically convenient one. Gary Frazer, assistant director for endangered species at the FWS, told Nature that he expects hundreds of thousands of people to comment.

Many of these will be rightly suspicious of the true motives. The proposed delisting of the grey wolf comes barely two years after the notorious ‘wolf rider’ that saw a clause to remove legal protection of the animals in Montana and Idaho tagged by local politicians to an unrelated, and essential, budget appropriations bill. The move, this journal noted at the time, set a “dangerous precedent” (see Nature 475, 5; 2011), and was the first time that Congress had removed a species from the list. The clumsy political manoeuvre came after a decade of court-rebuffed attempts to change the status of the wolf through the proper regulatory channels.

Grey wolves are certainly doing better in the United States than a century or so ago, when rewards for their killing made them locally extinct. Controlled reintroduction under the 1973 act has led to populations in the thousands around the Great Lakes and Northern Rockies — and to the loss of livestock. According to the US Department of Agriculture, between 1995 and 2007, wolves killed 298 cattle, 46 sheep, 13 llamas, 24 goats and 7 horses in Montana. Enough is enough, critics say; the grey wolf is no longer endangered. Yet the 1973 act is clear: such a judgement must be made over all, or a significant proportion, of the animal’s range.

Enough is enough, critics say; the grey wolf is no longer endangered.

“We still haven’t figured out how to handle a situation where experts have outspoken views,” Frazer says of the divergent opinions on the topic. It is a lament that will strike a chord with many policy-makers, not least those in Britain, where government-sanctioned marksmen are busy reducing the population of another emblematic — and previously protected — species. After years of similar arguments and conflicting scientific advice, the environment department DEFRA has embarked on two pilot culls of badgers, which farmers blame for the spread of bovine tuberculosis (TB).

Ian Boyd, science adviser to DEFRA, writes on page 159 that, too often, the evidence used to set policy is biased and un­reliable, even when published in scientific journals. He wants to introduce a Kitemark (indicator of quality approval) for studies that meet an audited standard of scientific evidence. But he should be careful what he wishes for. As Nature has repeatedly pointed out, the published evidence on badger culls does not indicate that bovine TB will be reduced by DEFRA’s strategy, which relies on untested tactics such as free shooting.

Politics can trump science, of course, for politicians are elected to make decisions. But so can sentiment. A few miles along the M4 motorway from where the badger culls and the protests against them are under way is the base of the Wolf Conservation Trust. Wolves vanished from Britain centuries ago, but they retain mystique and appeal — even to Brits. US lawmakers must bear this in mind as they invoke science to argue for the delisting of the grey wolf.

The protection of the 1973 Endangered Species Act for vulnerable animals does not end at the US border. Several overseas and foreign species are listed too, and US citizens are forbidden from, for instance, trading in them. But a US law that gives sanctuary to the Chinese alligator and the great Indian bustard but not to the native grey wolf would be a strange beast indeed.