The 70-year-old music teacher responsible for the massively supported - but ultimately failed - constitutional lawsuit against the CETA trade deal with Canada has set up a new campaign: to introduce national referendums in Germany.

Arguing that it is "fatal" to disregard the "majority's interests at the expense of millions of people and the environment," Marianne Grimmenstein said in her new online petition that there are a number of issues, from TTIP to bank bailouts to social benefits, that show that "citizens better make important decisions themselves."

But though the campaign has already gathered nearly 22,000 online signatures, she appears to be fighting an uphill constitutional battle. Germany is one of the few European countries where national referendums are banned - or at least so the conventional wisdom goes.

In fact, Grimmenstein argues, Article 20 (2) of the Basic Law (as Germany's constitution is known) not only specifically allows national referendums, but actually makes them essential to the German political system: "All state authority is derived from the people. It shall be exercised by the people through elections and other votes and through specific legislative, executive and judicial bodies."

As far as Grimmenstein is concerned, "other votes" includes referendums, which means there is no need to amend the constitution (requiring a two-thirds majority in both chambers of parliament) to create a law regulating national referendums. For that reason, her petition is aimed specifically at Angela Merkel's conservative party, the Christian Democratic Union (CDU), the only major party to be firmly against expanding direct democracy on a national level in Germany - turn the CDU, she argues, and the path is straightforward.

Legal problems

To back her up, Grimmenstein cites a handful of constitutional lawyers and law professors who share her interpretation, and quotes a 2012 comment piece written in the "Süddeutsche Zeitung" by writer and honorary law professor Heribert Prantl.

"The call for plebiscites on a national level is not an impertinence from civil society, but a still unfulfilled, yet unalterable central constitutional instruction," Prantl wrote.

But it's not that simple, says Uwe Lipinski, a constitutional lawyer based in Heidelberg. "Ms Grimmenstein and Mr Prantl would be right if you only read Article 20 (2) in isolation," he told DW. "The constitutional lawyer has to read several constitutional clauses in context with each other."

For one thing, most constitutional lawyers agree that Article 76 of the Basic Law defines Germany's legislative process very clearly, and contains no allowances for direct democracy at all. Any change to Germany's legislative process would require Article 76 to be amended - and therefore a two-thirds majority.

In fact, the constitutional court has already made a ruling to that effect, as part of the so-called "Lisbon ruling" of 2009, which decided to what extent the European Union's Lisbon Treaty was compatible with the German constitution.

"The constitutional court said, sure, national referendums can be introduced, if there's a change to the constitution, but they don't have to be," said Lipinski. "There's no obligation to introduce national referendums."

Lipinski describes himself as politically sympathetic to more direct democracy (parliaments are "just as likely" to make bad decisions as the people, he argues). But as a constitutional lawyer he can't help but see the massive headache that introducing national referendums would bring.

Many areas of the constitution that would need to be altered to make room for national referendums to create new laws. For instance: how would Germany's 16 states be integrated into a direct legislative process (the state governments make up the Bundesrat, the upper house of the German parliament)?

Article 79 (3) says that constitutional amendments are fundamentally inadmissible if they affect the states' involvement in the legislative process - in other words, the states have to be involved in making new laws, plebiscite or no plebiscite. "You can't just abolish the rights of the Bundesrat with a new law, or even just limit it," said Lipinski. "That's simply impossible."

Warnings from history

There are good historical reasons why the German constitution reserves so much power for parliament. In 1933, the new Nazi government introduced a law allowing the government to initiate referendums to pass new laws or even any of its "intended measures." This allowed, for instance, Adolf Hitler to meld the offices of Reich President and Reich Chancellor via a referendum in 1934.

There is also a longstanding theory that one of the reasons why the Weimar Republic collapsed was because its 1921 referendum law made it too easy for populist initiatives to overrule the elected parliament. This has been largely discredited by newer scholarship, says Lipinski, but it was certainly on the minds of the new Germany's founding fathers when West Germany was created in 1949 - As Germany's first president Theodor Heuss famously said, plebiscites are a "prize for every demagogue."