The phrase "separate issue" means that it is a different matter or problem, unrelated or distinct from the current topic or discussion. Full definition
Because the courts consider child support and custody as separate issues, they will not decide on custody based on its effect on child support, but on the needs of the child. (colesorrentino.com)
«But I think there are two entirely separate issues here and I don't think we should really be referring to religion when we're dealing with livestock exports,» he said. (theland.com.au)
And so you can't separate the issue of oil dependence from the issue of how we are producing generally — more energy generally. (dotearth.blogs.nytimes.com)