The Greens have lost their second co-deputy leader today.

Larissa Waters, like her predecessor, has been caught in a constitutional dual-citizenship confusion and has been forced to resign.

ABC Insiders, Barrie Cassidy spoke to the Thinkergirls about why this has occurred and why it is such an issue.

“There’s a rule,” Barrie said. “And the rule is in place that says you can’t have dual citizenship because then you’ve got divided loyalties.”

In a statement, Waters said: “It’s with great sadness that I have discovered I’m a dual citizen and that I’ll be forced to stand down from my position in the Senate, but I take full responsibility for this oversight. This was my fault and my fault alone. I just want to apologise to my party.”

“It’s a big loss,” Barrie said, “That’s the next generation of leadership gone from the Greens.”

Barrie believes the law is really outdated because all Australians were either born overseas, or one of their parents were born overseas.

“They should have checked, fair enough, well they’ve lost their jobs and they’ve paid a very high price for it,” he said. “This is an antiquated law.”