In December 2015, Ruane announced her intention to contest the
2016 Seanad election in the
Dublin University constituency as an independent candidate. She was elected to represent Trinity graduates in the
Oireachtas on the 15th and final count, unseating incumbent
Sean Barrett. She was re-elected in the
2020 Seanad election, reaching the quota on the eighth count. In the
25th Seanad, Ruane sits with the
Civil Engagement group; an alliance of independent senators seeking to bring civil society expertise and experience into the Oireachtas. In May 2017, Ruane introduced the Controlled Drugs and Harm Reduction Bill to the Seanad, which proposed
removing criminal sanctions for minor drug possession. The Bill was co-sponsored by then Senator
Aodhán Ó Ríordáin. In February 2019, Ruane introduced the Criminal Justice (Rehabilitative Periods) Bill to the Seanad, which proposed expanding access to
spent convictions, broadening the number and range of convictions that can be regarded as spent. The Bill passed final stage in the Seanad in June 2021 with unanimous support, including from the Government. In June 2021, Ruane introduced the Employment Equality (Amendment) (Non-Disclosure Agreements) Bill 2021 to the Seanad, which proposed restricting the use of non-disclosure agreements in incidents of workplace sexual harassment and discrimination. The Bill was developed in the context of the
MeToo movement, during which a significant number of people disclosed their experiences of sexual abuse or sexual harassment, including Zelda Perkins, a former assistant to film producer
Harvey Weinstein. The Bill garnered significant attention internationally, inspiring the development of similar legislation in a number of other jurisdictions. In October 2024, legislative amendments informed by Ruane's Bill were inserted by Minister
Roderic O'Gorman TD to the Maternity Protection, Employment Equality and Preservation of Certain Records Bill 2024, which was subsequently signed into law by President
Michael D. Higgins. In November 2021, Ruane introduced the Companies (Emission Reporting) Bill 2021 to the Seanad, which proposed to require companies to make disclosures regarding the greenhouse gas emissions caused by their activities annually, and to cause decreases in these emissions over time. The Bill successfully passed second stage consideration with cross-party support, despite the Government indicating its intention to impose a delay on the Bill. In May 2024, Ruane co-sponsored the Air Navigation and Transport (Arms Embargo) Bill 2024, which proposed restrictions on the transit and export of weapons of war from and through Ireland to Israel, and to cause inspections of planes seeking to transit weapons through the Irish territory and airspace. Minister
Eamon Ryan TD successfully sought to delay the future passage of the Bill for six months, stalling its progress. In October 2024, Ruane introduced the Parole (Special Advocates) Bill 2024 to the Seanad, which proposed the appointment of special advocates to represent the interests of parole applicants where certain information is withheld by the Parole Board in its consideration of the application. She was re-elected at the
2025 Seanad election. Ruane has been referred to as "a long-time campaigner for
drug reform in Ireland." She and
Green Party TD Neasa Hourigan have called for a
citizens' assembly on drugs. Ruane asserts that drug prohibition has never worked and in 2021 signed an open letter with over 100 Irish youth workers and former youth workers calling for an end to drug prohibition and for the legal regulation of drugs in Ireland. The letter has also been signed by Senator
Eileen Flynn. Ruane is a member of the
Joint Oireachtas Committees on Children, Equality, Disability, Integration and Youth, and Justice, in addition to being vice-chair of the special Joint Oireachtas Committee on Drugs Use, She was formerly vice-chair of the special Joint Oireachtas Committee on the
Eighth Amendment, which was established to examine the repeal of Ireland's constitutional ban on abortion and recommend the legal grounds to access an
abortion in Ireland.
Miriam Lord of
The Irish Times named Ruane her 2016 Senator of the Year. == Work outside of politics ==