Extension of Term of Patent Right
Patent life is 20 years from filing both in JP and US, but in both countries if a drug undergoes clinical trial and review period, the enforcement term of the patent which covers the drug can be extended up to 5 years.
Difference between JP and US:
JP patent system:
Japanese Patent Law, Article 67 (2): Where there is a period during which the patented invention is unable to be worked because approvals prescribed … to ensure the safety (i.e. of pharmaceutical and agricultural products)…, patent right may be extended … by a period not exceeding 5 years.
Another improvement: Recent amendment to JP Patent Law took away requirement for at least two years of clinical trial.
US patent system:
US Patent Law, 35 USC § 156 (paraphrased): Up to five years of extension for (1) 1/2 of IND (Investigational New Drug) period and full review period; but (2) total period of remaining patent term including the extension cannot exceed 14 years from approval; and (3) only one patent extension for one product (active ingredient).