Green Party Leader Elizabeth May is joining a chorus of concern about a Conservative law that revokes citizenship from convicted terrorists, days after the government used the new provision for the first time.

, May said Conservative Leader Stephen Harper embarked on a 鈥渧ery slippery slope鈥 when his government passed Bill C-42, a controversial law that allows Canada to strip dual citizens who are convicted terrorists of their citizenship and deport them. 

鈥淭he only grounds on which someone should be stripped of citizenship is if they obtained their citizenship through fraud,鈥 said May. 鈥淥nce you start the concept that there are different classes of citizenship and sub-citizens are lesser citizens than others, you鈥檙e on a very slippery slope.鈥

On Saturday, . 

One day later, the saying that terrorists should get to keep their Canadian citizenship, as removing it makes citizenship 鈥渃onditional on good behaviour.鈥 At the, Trudeau maintained his position, saying that convicted terrorists should be thrown in jail -- not have their citizenship revoked.

May echoed Trudeau鈥檚 beliefs Tuesday, adding that Bill C-24 was all about votes from the get go.

鈥淪hould people who commit crimes be put in jail for the rest of their lives? Absolutely,鈥 said May. 鈥淚t (Bill C-24) was about vote getting in this election. It was about dividing people, twisting and spinning and avoiding some fundamental principles of Canadian citizenship.鈥

May was not invited to take part in Monday night鈥檚 debate. She did, however, have lots to say about it, particularly on the exchanges pertaining to climate change. May said Harper鈥檚 claim that greenhouse gas emissions have reduced under his government is 鈥渘ot technically correct.鈥

鈥淯nless Stephen Harper wants to take person credit for the economic downtown in 2008 鈥 he can鈥檛 take any credit whatsoever for the reduction in greenhouse gases that occurred in 2008, 2009. And ever since our economy began to recover, our greenhouse gas levels have been rising,鈥 said May. 

, annual greenhouse gas (GHG) emissions have fallen twice since 2006. GHGs fell from 761 megatons in 2007 to 741 megatons in 2008, and then again to 699 megatons in 2009. says the reason for the decrease was the global recession. GHGs began steadily increasing again from 2009 to 2013.

May took to Twitter to post her foreign policy positions during the leaders鈥 debate, as she did during the Globe and Mail debate on Sept. 17. But her performance was significantly poorer on Monday night, according to data from Twitter Canada. May only had 1,144 mentions on the social media platform Monday night, compared to 14,161 during the Globe debate.