has managed to convince the US patent office that it should hold the patent for encouraging consumers to write reviews of items they've purchased by determining the optimal times to send them emails or reminders. The move means that sites that offer their customers the chance to write a review of a product they have purchased could theoretically have to pay a levy to the online retailer for the privilege of offering such a service. It could also affect review sites like Pocket-lint who lets its readers comment on their experiences of any product we've reviewed.

According to “In one embodiment of the patent, the system sends consumers a message inviting them to write a review in a predetermined amount of time after the purchase. It's a method widely used by online retailers, including Yahoo Shopping. The patent also covers the method of tracking who returns to rate products by asking them to click on a unique link in an email. But the patent even covers collecting reviews by letting visitors to a Web site fill out a form.

Craig Berman, an spokesman, said he couldn't speculate on whether the company would attempt to license its new intellectual property.