 Sainsevain was a delegate to the 1849 California Constitutional Convention in Monterey.In 1859, Sainsevain sold Rancho Cañada del Rincon en el Rio San Lorenzo, and with his brother, Jean Louis, bought the El Aliso vineyards in Los Angeles from their uncle, Jean-Louis Vignes (also known as "Don Luis Del Aliso").The firm of Sainsevain Brothers, immediately proceeded to expand the scale of operations at the old El Aliso vineyard.