He is best known for drafting, and organizing the campaign for, Proposition 103, a ballot proposal that rolled back automobile insurance rates in California.

The campaign encouraged community members to give up smoking for a day and donate the monetary equivalent of a pack of cigarettes to a scholarship fund.

After graduating magna cum laude in 1974,[6] Rosenfield moved to Washington, D.C. to intern with Massachusetts Congressman Michael Harrington.

Three years later, after graduating from Georgetown, Rosenfield began working full-time for Nader's Public Citizen Congress Watch as an energy lobbyist opposing nuclear power in 1979.

As program director, he lobbied on a variety of issues including utility and campaign finance reform and public access to government.

Proposition 51 passed, but Rosenfield continued to work for insurance rate reductions with his newly formed public interest group.

[citation needed] In 1987, Rosenfield began to write a ballot box proposal and formed a campaign to sponsor it called Voter Revolt.

The insurance industry, fearing they would not be able to defeat Proposition 103, launched three competing initiative measures in an attempt to confuse voters.

[10] To bring attention to his cause, Rosenfield used grassroots publicity stunts like having guards accompany him while he delivered the signatures that put Proposition 103 on the ballot.

These stunts, many 18-hour days, canvassers knocking on 1 million doors, and the high-profile endorsement of his mentor, Ralph Nader, helped Voter Revolt pass the initiative in November 1988.

In 2012, an initiative to control health insurance costs similarly to Prop 103 received over 800,000 signatures and earned a place on the 2014 ballot.

"[18] Proposition 103's benefits to policyholders have been questioned by independent researchers, including the International Center for Law & Economics.

He and his colleague Jamie Court created Californians for Quality Care (a division of Consumer Watchdog) to spearhead the effort.

Rosenfield co-authored Proposition 9 in 1998, a ballot initiative to block aspects of the utility deregulation laws passed by California lawmakers in 1996.

He also works with Consumer Watchdog in administrative and judicial proceedings to lower insurance rates and enforce Proposition 103.