[8][9] Hsiung ran for mayor of Berkeley, California, in 2020, largely focused on the issue of animal rights, and earned 24% of the vote, defeated by incumbent Jesse Arreguin.

[10][11] Hsiung was incarcerated in November 2023 after being convicted of felony trespassing for his role in an open rescue of sick and dying chickens from Sunrise Farms in 2018.

He received a National Science Foundation graduate fellowship to study economics at the Massachusetts Institute of Technology, but he went on leave after his first year to pursue a joint JD/PhD.

[citation needed] He coauthored an analysis of the effect of climate change on nonhuman animals with behavioral law and economics scholar Cass Sunstein.

Hsiung and Direct Action Everywhere protesters climbed over a barbed wire fence to enter an egg farm and take video of alleged animal abuses such as confinement, preening from stress, and lack of water.

[23] In April 2016, Hsiung and two other members of DxE went to Yulin, China, the location of the infamous Dog Meat Festival, to document the animal cruelty.

[34] On April 24, 2018, Hsiung was arrested and charged with "threatening bodily injury" in Boulder, Colorado, at Whole Foods after asking questions at the store about the source of its meat products.

"[35] In May 2018, Hsiung and other protesters walked into a Santa Rosa Egg Farms facility, rescued chickens, and recorded extensive video footage which illustrated systemic animal abuse, massacre and mutilation.

[37] The opinion asserts that California Penal Code Section 597e and the common law doctrine of necessity permit the removal of sick and dying animals in certain situations, including from commercial facilities DxE investigated.

[citation needed][37][41] Hsiung has also been a part of several other high-profile protests and incidents, most notably a disruption of a San Francisco Giants-LA Dodgers baseball game in September 2016 that led to him being tackled by Giants player Angel Pagan on national TV.

Hsiung represented himself in the proceedings, and he received a suspended sentence with 24 months of supervised probation and was required to pay the farmer US$250 as the value of the stolen goat.

[49] While focused on animal rights, his platform also included converting under-utilized corporate property into permanent supportive housing for individuals experiencing homelessness; accelerating Berkeley's carbon-neutral timeline to 2025; creating a plant-based, pedestrian-only, and fossil fuel-free "Green District"; and transitioning the Berkeley Police Department away from allegedly aggressive law enforcement to community health and support.

In 2024, Harvard Law Review published an article co-written by Hsiung, Justin Marceau, and Steffen Seitz called, Voluntary Prosecution and the Case of Animal Rescue.