Patent Infringement Litigation: Evidence Collection and Damages Calculation

In patent infringement litigation, evidence collection and damages calculation are decisive factors. Enterprises must prepare thoroughly before filing suit.

1. Core Evidence Types

Patent right evidence: patent certificate, annual fee payment receipts, patent register copy, claims. Infringement evidence: accused infringing product samples, purchase vouchers, notarial certificates, webpage screenshots. Damages evidence: infringer's sales data, financial statements, advertising materials, industry profit margin data.

2. Evidence Collection Methods

Notarized purchase is the most common method, with a notary supervising the entire purchase process and issuing a notarial certificate. Pre-litigation evidence preservation may be applied for from the court (in urgent situations). Third-party investigation agencies may be engaged to collect infringement leads. For process patents, the court may be requested to order the infringer to produce evidence in its possession.

3. Damages Calculation Methods

Damages are determined in the following order: actual loss of the rights holder → illegal profits of the infringer → reasonable multiple of patent licensing fee → statutory damages (RMB 500 to RMB 5 million). Actual loss may be calculated as total reduction in patented product sales multiplied by reasonable profit per patented product. Infringer's profits may be calculated as infringing product sales multiplied by reasonable profit per infringing product.

4. Punitive Damages

For intentional patent infringement with serious circumstances, damages may be set at 1 to 5 times the amount determined by the above methods. Punitive damages require the rights holder to actively claim them and prove the infringer's subjective intent and serious circumstances (e.g., large-scale infringement, long duration, failure to cease after warning).