On Sept. 16, new methods of challenging patents before the Patent and Trademark Office (PTO) went into effect, thanks to the America Invents Act. Three of the four methods available to businesses now are brand-new, and similar to litigation. The last, ex parte re-examination, has been around for a while, but is pricier in this incarnation.

Our December issue guides in-house counsel through each of these methods and advises companies to carefully consider their options before challenging a patent. Each of the methods has “distinct advantages and disadvantages,” according to Reed Smith Partner Marc Kaufman. In this cheat sheet, we’ll sum up what you need to know about each of the options to bring a challenge before the PTO.

Ex parte re-examination

Though the cost for this method has increased from $2,520 per challenged patent to $17,750 per challenged patent, it remains the cheapest option. At any point after a patent issues, you can provide the PTO with evidence that it was anticipated by printed publications or another patent. A patent examiner will investigate and come to a conclusion, with no effort required on the part of the challenger.

However, leaving your challenge in the hands of an examiner means that you won’t be able to advocate for your position. If the examiner upholds the patent, you can try again using one of the other three methods.

Inter partes review

Like ex parte re-examination, inter partes review is for challenges that claim a patent was anticipated by another patent or by a printed publication. Unlike ex parte re-examination, this method can’t be used during the first nine months after a patent is issued and requires the challenger’s active participation.

Inter partes review is a lot like litigation in that there are declarations by experts, depositions, orders and a trial in front of PTO administrative law judges.  Discovery is more limited and proceedings are more streamlined in inter partes review than in litigation, so while it doesn’t come cheap, it is still cheaper than going to court. And faster—the PTO claims that nearly all inter partes reviews will be decided within 12 months.

Post-grant review

Post-grant review is a lot like inter partes review, in that it is structured similarly to litigation. But while inter partes review only allows for anticipatory challenges, post-grant review enables you to challenge a patent on any grounds of invalidity. You can seek post-grant review only during the first nine months after a patent has issued, starting with patents filed on or after March 16, 2013.

The downside to post-grant review is that it comes with a broad estoppel on any claim of invalidity that you raise, which would prevent you from challenging the same patent in other proceedings. If post-grant review seems like the best option for your company, you need to make sure you have all of your strongest arguments at the ready, because you may not get another chance to challenge that patent.

The transitional program for covered business method patents

Aside from being a mouthful to say, the transitional program for covered business method patents is a way to specifically attack patents on financial products or services. It is similar to post-grant review in that you’re able to challenge the patent on any grounds of invalidity, but it is only available as an option if you have been sued for infringing the challenged patent, or have a reasonable fear that you will be sued.

There is also some question as to what exactly constitutes a financial product or service. According to Reed Smith Partner Marc Kaufman, “the definition is unclear.”

For patents that issue before March 16, 2013, business can use this program to challenge them right away. After that date, you’ll have to wait nine months before challenging the patent.