Grace Period/Prior knowledge
Novelty of an invention is not destroyed by disclosure prior to the filing date of the application or convention priority date without the patentee's knowledge or consent, provided that the matter disclosed was derived or obtained from the patentee, the invention had not been used by the patentee or his predecessor in title in Zimbabwe prior to the filing date or priority date, other than for the purpose of reasonable technical trial thereof, and the application was filed with reasonable diligence after learning of the disclosure.
Patent applications are examined as to compliance with formal requirements.
Duration & Maintenance
A patent is valid for 20 years calculated from the filing date or international filing date, subject to payment of annual renewal fees. A six-month grace period is available (subject to surcharges). Renewal fees are payable and are calculated from the first anniversary of filing. A six months grace period is provided for payment of renewal fees, subject to payment of surcharges. If a renewal fee is not paid within this period, the patent lapses.
Patent must be worked within four years from date of filing or three years from date of grant, whichever period expires last. A compulsory licence may be granted if patent is not worked.