I'll start with the low-hanging fruit. Ask people one result of the Civil War and they'll no doubt point to the end of slavery. The Thirteenth Amendment abolished slavery and involuntary servitude in the United States. In addition to prohibiting slavery, it also arguably prohibits specific performance as a remedy in service contract cases (but see this fascinating law review counterargument in Specific Performance and the Thirteenth Amendment).
Following the Civil War, the United States also ratified the Fourteenth Amendment, including the equal protection and due process clauses. These clauses have been used to afford public employees with procedural safeguards, and protection from discrimination. Additionally, courts have used the Fourteenth to "incorporate" parts of the bill of rights to apply to public employment. For example, public employees receive limited free speech protection by incorporating the First Amendment to apply to state actors. First Amendment incorporation has also been used to afford employees unemployment compensation where they lose their jobs due to work-religion conflicts.
There are also more tenuous links to modern employment law. For example, Title VII is part of the civil rights acts of 1964. Would it have been enacted, and would it even be considered constitutional if not for the Civil War? Its precursor, the Civil Rights Act of 1875 was passed shortly after the Civil War, although that act was declared unconstitutonal because it applied to non-state actors. The Supreme Court later upheld the Civil Rights Act of 1964, not under the Fourteenth Amendment (although some Justices advocated that route), but under the interstate commerce clause.
Also, the Fifteenth Amendment protects the right to vote regardless of race or color. Would antidiscrimination laws at the local, state, and federal level be the same if the people intended to be protected couldn't vote? Sure, we'll never know what an alternate present would look like, but surely the voting rights had some impact on legislation.
That's just a rundown of Civil War impacts on employment law off the top of my head. Please drop a comment if you have any other ideas!
Image: Unidentified Union soldier; public domain from Library of Congress Civil War collection.
Posted by Philip Miles, an attorney with McQuaide Blasko in State College, Pennsylvania in the firm's civil litigation and labor and employment law practice groups.