Nigeria, March 7 -- When a senior and respected lawyer appears before a foreign tribunal bearing official-looking documents from his home country, the court is entitled to presume that those documents carry the authentic voice of the state. International litigation relies on that quiet presumption of trust. Without it, the recognition of foreign documents in international litigation would descend into chaos. But what happens when the document - and the supposed voice of the state that speaks through it - turns out to be nothing more than an expertly crafted counterfeit?

That question lies at the heart of the extraordinary saga surrounding a modest house at 79 Randall Avenue in North London - allegedly bought in 1993 with Nigeria's stolen...