Whether the cantonal court could use Art. 9 OLE and au pair standards to determine wage and working conditions for an unauthorized foreign worker.
Yes. An unauthorized foreign worker may invoke Art. 9 OLE via Art. 342(2) CO, and the cantonal court could rely on au pair-specific standards and the cantonal employment office letter.
Art. 9 OLE serves not only to protect Swiss labor market conditions but also foreign workers. For au pair work, the relevant benchmarks are the rules and usages governing that specific activity, not a domestic household contract-type.