Thielen, as an environmental attorney before she got into politics, fought for Hawaiian access to the Navy's former bombing range at Kaho'olawe and opposed the H-3 Freeway because of the potential for Windward sprawl. She also worked with the poor as an attorney with the Legal Aid Society of Hawai'i. She is a direct descendant of the American patriot Patrick Henry ("Give Me Liberty or Give Me Death!") — but said she respects the sovereignty rights of Hawaiians and their spiritual connection to the Islands.

"I developed very deep roots with the Hawaiian community," she said of her legal work with Protect Kaho'olawe 'Ohana. "Those are bonds I will always cherish."