This is a multicenter, open-label trial to assess the long-term safety and efficacy of Cannabidiol Oral Solution as adjunctive therapy for pediatric and adult participants with treatment-resistant seizure disorders, including Lennox-Gastaut syndrome (LGS) or Dravet syndrome (DS). All participants have rolled over from previous trials: INS011-14-029 (NCT02324673), INS011-14-024 (NCT02318537), or INS011- 14-025 (NCT02318563).