Facebook founder and CEO Mark Zuckerberg and his wife, Priscilla Chan, this week made a $500,000 contribution to the campaign to decriminalize small amounts of illicit drugs in Oregon.

The contribution was made Thursday by Chan Zuckerberg Initiative Advocacy, the political arm of the couple’s philanthropic organization, according to Oregon Secretary of State records. The initiative focuses on science, criminal justice reform and education, according to its website.

The contribution makes the couple the second-largest financial backers of Measure 110.

The largest financial supporter is Drug Policy Action, the advocacy and political arm of the Drug Policy Alliance, a national advocacy group backed by investor and philanthropist George Soros and based in New York. The organization, which was a major supporter of Oregon’s marijuana legalization measure in 2014, so far has given about $862,00 to the campaign, campaign finance records show.

Measure 110 would remove criminal penalties for personal, noncommercial possession of drugs listed as Schedule I, II, III, or IV by the federal Controlled Substances Act, including heroin, methamphetamine and Ecstasy.

Possession of small quantities for personal consumption would be reduced from misdemeanors to violations, which are similar to speeding tickets. People caught with small amounts of drugs would be connected to drug treatment and recovery services.

The measure would also redirect most revenue generated through recreational marijuana sales toward drug abuse treatment.