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A Guide to Patent Searching

NIC Document


This guide explains how to perform simple searches for patent information, using both commercial and free resources. It covers the reasons for searching, where to find the tools and how to conduct the search.

In Brief

  1. Reasons for carrying out a patent search
  2. Where to find resource tools
  3. How to conduct a patent search
  4. Commercial databases and services


Patent searches can give you vital information about the novelty of an invention and possible infringement of other patents. You can use free online resources to search patent databases yourself or use commercial organisations that perform patent searches on your behalf, such as patent attorneys, private searching services libraries and the UK Patent Office. Commercial patent searching services have access to more sophisticated search tools and expertise, but can be expensive. Using free, online patent search tools can also provide useful results, but full patent searches are very time consuming. When performing a patent search, it is important to use different search terms and strategies. It is good practice to do a patent search yourself before getting a search done by a patent attorney. However, no patent search should be considered exhaustive.

Reasons for carrying out a patent search

It is important not to limit your search to just checking whether an invention has already been patented. You need to include other published data such as scientific papers. Commonly known as prior art searches, these refer to all information about an invention disclosed to the public before the priority date. The priority date is the date you submit your patent application. Prior art includes any patents related to your invention, any published articles on the idea and any public demonstrations. As part of the patent application process, the Patent Office carries out its own patent search. This is used to determine patentability, validity and novelty. In the UK, the Patent Office can make the results of this search available before a patent application is made public. This allows you to obtain an early and relatively cheap search compared with the searches carried out for International Patent Cooperation Treaty (PCT) or other patent applications.

Where to find resource tools

The internet is the main source for finding patents. The three major patent offices (Europe, Japan, US) and the World International Patent Organization (WIPO) all provide free, flexible, and effective access to their databases via the Internet:

  • UK Intellectual Property Office www.ipo.gov.uk
  • European Patent Office www.epo.org
  • United States Patent and Trademark Office www.uspto.gov
  • World Intellectual Property Organization www.wipo.int
  • Japan Patent Office (English search interface) www.jpo.go.jp
  • Google patent search www.google.com/patents
  • How to conduct a patent search

    Each of the free internet patent databases has slightly different search parameters and systems, although there are several common threads. The most straightforward method of searching is to use the patent document classifications system in conjunction with keywords.


    Patent Offices classify patents by a standardised scheme covering different technical domains. This scheme is called the International Patent Classification (IPC) and is administered by the World Intellectual Property Organisation (WIPO). The IPC is based on a hierarchical system, in which industrial technology is divided into a range of sections, classes, subclasses, and groups. The easiest method of finding the appropriate domains is to perform an initial keyword search to find patents that are similar to your proposed idea and use their classifications to identify potential competing patents. If your patent application has already been filed, the Patent Office will identify the appropriate IPC domains which you can then use for further searching. You can find a guide to the most recent version of the IPC on the WIPO website at: http://www.wipo.int The IPC uses a symbolic system, which can be broken down to give a detailed description of a subject area. A complete classification symbol is broken down into four levels: Section – Class – Subclass – Main Group or Subgroup.

    Typical example:


    In this case:

    Subgroup – 20/12 (the Main Group would be 20/00) THE HEAT BEING GENERATED BY FRICTION; FRICTION WELDING

    The complete symbol above represents friction welding operations although the full hierarchical description is more complex. You can find the full range of IPC classifications and symbols at: http://www.wipo.int


    Searches by keyword break down the documents brought up by a classification search. Searching by keyword alone can produce too many results to be reasonably analysed, while narrowing down your search can mean you run the risk of missing important results. When searching using keywords, you should think of other words to describe the same concept. This is because a single search term will rarely produce all the desired results. You should structure the search procedure by:

  • Defining the invention
  • What it does
  • How it works
  • What it solves
  • By what means
  • What it is made of
  • If it is used as part of a greater thing
  • The end result

    Date, inventors and assignees

    You can then search further by date, inventor, and assignee (i.e. the company that owns the invention). You can enhance your search with good background knowledge of the technical area and the major players involved in that area.

    Commercial databases and services

    As well as using the free resources available, you can also gain access to commercially maintained databases of patent information. The best of these give you more searching power and useful analytical tools, taking some of the hard work out of searching and improving results. You can find a list of organisations offering these services at: www.epo.org You may find it more cost effective to employ a professional searching service than using free patent search resources. A patent searching professional is likely to be more experienced in formulating search queries and will have better understanding of the tools available. Although it is possible to carry out effective searches using free resources, it can be very time consuming, and complex searches may require specialist services. In many cases, the title and abstract of patents are written in a way that makes them difficult to identify by using keyword searches. Patent databases such as Derwent World Patents Index systematically rewrite patent titles and abstracts to put them into a more accessible form.

    You may also be interested in the following NIC document: Protecting your idea – Patents, Designs, Copyright and Confidentiality