 From 1844 to 1851, LeGrand served as Associate Judge of the Sixth Judicial Circuit of Maryland.In 1851, he was appointed Chief Judge of the Maryland Court of Appeals, where he served until 1861.LeGrand was defeated for re-election by Unionist candidate Silas Morris Cochran, after a letter he wrote to the "Baltimore Sun" calling for Maryland to secede from the United States was publicized.