Germany's lower house of parliament, the Bundestag, has a whopping 709 seats. This makes it the second-largest legislative body in the world. That number could balloon to well over 900 after Germany's federal elections on September 26.

The problem this poses is greater than a crunch to fit that many chairs in the chamber. How can compromises be made, and how can backbenchers be heard, in a parliament so unwieldy?

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Why is the Bundestag so big?

When Germans vote for their federal government, they vote not just directly for their local member of parliament. The so-called "second vote" counts for a political party and its list of candidates. This is meant to combine the principles of majority rule and proportional representation.

The system was conceived in postwar Germany as a compromise with smaller parties, who worried they would consistently fail to win seats, along with assuaging concerns about instability that had come with political fragmentation before the war.

As it stands now, Germany has 299 electoral districts. This means that the Bundestag should in theory have 598 seats.

But if a party wins more seats than it's entitled to, based on the share of second vote results, they are allowed to keep them. These are called "overhang" seats. To make up for this, overall other parties also get more seats, to ensure that the relative proportion of parties in the Bundestag reflects the election result. 

In the last federal election in September 2017, that resulted in a total of 111 extra seats. 

What led to the dramatic increase?

"This worked well when Germany had two big parties; that is, two parties that received the vast majority of votes," explained constitutional law professor Sophie Schönberger, referring to Angela Merkel's Christian Democrats (CDU) and the the center-left Social Democrats (SPD), which could be characterized as a rival at some times and partner at others.

For decades after World War II, either the SPD or the CDU easily captured a majority of the overall vote, as well as most of the direct mandates in the constituencies.

But with an ascendant Green Party, as well as the small-but-resilient socialist Left Party — not to mention the pro-free market Free Democrats (FDP) and the populist far-right Alternative for Germany (AfD) — the electoral map isn't as two-tone as it was before.

Instead of two big parties, "we have three medium-sized ones and a smattering of a few others," Schönberger said, with the Greens as number three.

"This creates a vicious circle, in which there have to be more and more lawmakers from each party in order to maintain the balance of power," said comparative politics researcher Klaus Stüwe, pointing out that a 2012 ruling from Germany's top court stipulated that the number of overhang seats could not be capped.

Things have become even more complicated, he explained, as people may use their first vote not for the candidate of the party they prefer, but for one who they assume has a chance of getting past the rival they do not. "In the last 30 years, more people are splitting their ticket," Stüwe observes. 

What's the problem with having a big Bundestag?

Considering it is "not unlikely" that the Bundestag get bigger than it has ever been after September's vote, Schönberger expects this to translate into problems for German democracy.

"There is the issue of the increasing impossibility of ensuring healthy and concise debate, as well as the problem of whether 'backbenchers' will ever get a chance to speak," Schönberger said. "And there is the question of the cost of paying the salaries of so many lawmakers," she added.

Members of the Bundestag earn a little more than €10,000 ($11,800) per month before taxes, and in addition are given tax-free spending money of €4,560 per month. They also receive €12,000 to outfit their office.

Each lawmaker employs staff while in office, and receives a generous pension when they retire. An ever-expanding Bundestag, therefore, means an ever-expanding burden on taxpayers.

"It was a good idea, trying to combine the best of both worlds," Stüwe said. "But now, our electoral system has become so complex that people don't even understand it anymore."

What reform efforts have been made?

In recent years, the FDP, Greens, and Left Party have forged an alliance to lobby for a significant decrease in the number of districts.

"That wouldn't fix everything, but it would help," Schönberger said.

Stüwe agreed that a reduction in the number of districts is the only "viable" solution, but added that the CDU'S Bavarian sister party, the CSU, has put up strong resistance to a drastic reduction. This is because it benefits the most from the current setup, as it wins most constituencies in Bavaria, Germany's second-largest state by population.

The grand coalition of the SPD and CDU that is currently in power agreed to a slight cutback in constituencies to 280 — which may be implemented for the next federal elections in 2025.

While you're here: Every Tuesday, DW editors round up what is happening in German politics and society, with an eye toward understanding this year’s elections and beyond. You can sign up here for the weekly email newsletter Berlin Briefing, to stay on top of developments as Germany enters the post-Merkel era.