US (and French) Courts Have Ruled Head-of-State Immunity is Absolute
It is clear that the entrapment and forced landing in Austria of the official airplane carrying Bolivian President Evo Morales was the work of the US, which was obviously behind the decision by France and Portugal to deny air rights to the flight, and which also was obviously behind the Austrian government’s demand to be allowed to search the jet after it landed. After all, those countries have no interest themselves in capturing US National Security Agency whistleblower Edward Snowden, who is only Obama’s and the NSA’s quarry. (A Spanish official said Spain was "told" Snowden was on the plane but wouldn't say by what country. Let's guess who would do that!)
So given that the US was behind the Morales "kidnap" outrage, it is worth examining how the US has historically viewed the legal status of heads of state under international law and custom when they are traveling.
In 2004, the US Court of Appeals for the Second Circuit (New York) ruled that Robert Mugabe, the corrupt and brutal leader of Zimbabwe, enjoyed “absolute immunity” while inside the US on a visit to New York. The decision stemmed from 2001, when a group of citizens of Zimbabwe sought to have Mugabe arrested in New York on charges of “extrajudicial killing, torture, terrorism, rape, beatings and other acts of violence and destruction.” A month earlier, the US Court of Appeals for the Seventh Circuit (Chicago), reached a similar conclusion in a case involving then Chinese President Jiang Zemin.
The US government had filed briefs in both those cases arguing that both Jiang and Mugabe (as well as Mugabe’s foreign minister, who was traveling with him), had absolute immunity as traveling heads of state. Interestingly, the US brief, in addition to citing the Vienna Convention, cited the 1976 Foreign Sovereign Immunities Act (FSIA), signed into law by Pres. Gerald Ford, which among other things makes sovereign leaders absolutely immune. Ironically, that law was successfully used by by leaders of Saudi Arabia to convince US courts to immunize them against civil suits filed against them by victims of the 9-11 attacks, who had claimed Saudi leaders had funded the attacks.
No surprise that the US would want sovereign immunity, given that the head of state of the US at the time of the court proceedings and the Appellate Court hearing, George W. Bush, and his vice president Dick Cheney, were already themselves guilty of serious war crimes and crimes against humanity for their illegal invasion of Iraq, their authorization of kidnappings, extrajudicial killings and torture, and their financing of acts of terrorism. They understandably wanted to establish that nobody should even think about trying to embarrass them with an arrest warrant for these crimes during any trips abroad.