Unless you are a member of a union that has a contract that includes seniority promotion guidelines, a company has no obligation to recognize seniority and can apply different rules. The only prohibition is that the different treatment cannot be based on race, ethnicity (this does not necessarily mean what language you speak - speaking a certain language can be a requirement if it is relevant to the job), religion, gender, marital status, age or in some jurisdictions sexual orientation or pregnancy.
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