Some time in early September, Judge John Roberts, who has been nominated by President George W. Bush to sit on the US Supreme Court, will go before a committee of senators and try to explain his reasoning on why an endangered California toad can only be protected by the federal government if it hops across the border to Nevada.

The brief dissenting opinion on the arroyo toad is one of the few authored by Mr Roberts during his two years on the US Court of the Appeals, one level below the Supreme Court, and underscores why the liberal groups fighting Mr Bush on the nomination will face such a difficult task as they try to muster votes against him over the next month.