Her father was born in England and came to Australia at the age of 12 as part of a child migration scheme, initially living at Fairbridge Farm.

[1] In 2013, Lines was nominated by the ALP to fill a casual vacancy caused by the resignation of Senator Chris Evans, another former United Voice official.

[citation needed] In 2018, as chair of the Senate's procedure committee, she led an inquiry into the use of the Lord's Prayer to open parliamentary sittings which recommended that the practice should continue.

In 2014, she stated that immigration minister Scott Morrison had "blood on his hands" following the death of Reza Barati at the Manus Regional Processing Centre.

[11] In 2016 she was one of four Labor MPs to publicly call for all detainees on Manus Island to be settled in Australia, in opposition to existing party policy.

In response, Alexander Ryvchin of the Executive Council of Australian Jewry accused her of "play[ing] to people's fears and prejudices" and making "dog-whistle allusions to supposed Israel lobby influence over Australian politics".

In January 2021 she stated that it "celebrates white supremacy and the legacy of colonisation that is directly linked to the various ways we continue to fail First Nations people".