Earlier this morning (Australian time) a judge has agreed to block parts of Arizona’s controversial anti-migration law, which is opposed by the Obama Administration, from coming into force today. Judge Susan Bolton, of the United States District Court, has issued a temporary injunction in Phoenix after an application by the Obama Administration.

The Arizona law, signed off by Republican governor Jan Brewer in April this year, requires police officers to check a person’s immigration status and arrest people who are not carrying papers; allows for warrantless arrests of migrants without papers and allows for people to be forcibly deported.

The Obama Administration has brought legal action to have the law declared unconstitutional, principally on the ground that it is only Washington that can regulate border control. Other opponents of the law say it would encourage racial profiling.

Judge Botlon’s 36-page ruling argues the interests of the United States federal government in making policy and regulating migration will be “irreparably harmed” if the Arizona law is allowed to start operation today. Judge Bolton sympathised with the argument that if the law were implemented thousands of people in Arizona would have to be wrongfully detained by police so their migration status was checked.

And, significantly for the opponents of the law, Judge Bolton has found that many of the arguments being mounted by the Obama Administration against the Arizona law are “likely to succeed on the merits”. In other words, the Arizona law could be doomed to failure.

Immigration is a hot-button issue in Arizona in the same way it is in Australia and, as is the case here, the anti-immigration lobby justifies its draconian laws on the basis it must act as a deterrent to Latinos crossing the US/Mexico border. And in Arizona and Australia, it is the courts that have intervened on occasion to inject justice and fairness into the system.

If the Arizona anti-migration law does ultimately fail in the courts, then it will principally be because legislators in that state, panicked by community fear whipped up by media and fringe groups, rushed to pass an ill-conceived law. There is a lesson in this for Australian politicians such as opposition leader Tony Abbott and Prime Minister Julia Gillard as they knee-jerk their way through this election campaign on the issue of boat arrivals.