Thank you for your question. Since your question did not provide any specific scenario I will take you to FAR part 22 which cover labor laws to answer your question. First I want to explain why I am referring to the Service Contract Labor Standards (SCLS) rather than SCA which was used in your question. FAR 22.1000 tells us that there has the Service Contract Act of 1965 is now known as the Service Contract Labor Standards. Now we can move into when the SCLS applies, FAR 22.1002-1 states "service contracts over $2,500 shall contain mandatory provisions regarding minimum wages and fringe benefits, safe and sanitary working conditions, notification to employees of the minimum allowable compensation, and equivalent Federal employee classifications and wage rates." FAR 22.1003-1 further states "This subpart  22.10 applies to all Government contracts, the principal purpose of which is to furnish services in the United States through the use of service employees, except as exempted in 22.1003-3 and 22.1003-4 of this section, or any subcontract at any tier thereunder. This subpart does not apply to individual contract requirements for services in contracts not having as their principal purpose the furnishing of services. The nomenclature, type, or particular form of contract used by contracting agencies is not determinative of coverage." So unless the exemptions apply to your scenario then the contract would be subject to the SCLS. Hopefully this answer provides the information for you to help determine whether the SCLS applies to your acquisition or not.