The primary impetus for the 2004 Act was the need to implement a number of technical changes to substantive patent law as a result of the 2000 revision of the European Patent Convention of 1973.

Although many of the changes (such as the amendments to provisions restricting the scope for UK residents to file patent applications abroad) will be of greatest significance for patent attorneys, a number of provisions are of importance to lawyers.

Employee inventors whose patents belong by virtue of section 39 of the Patents Act 1977 (1977 Act) to their employers can seek compensation on the basis that these patents are of "outstanding benefit" to their employer, having regard, among other things, to the size and nature of the employer's undertaking (section 40, 1977 Act).

No successful application has ever been made under the 1977 Act by employee inventors seeking compensation. The 2004 Act seeks to make the hurdle for employees slightly lower by testing the outstanding benefit as against not only the patent, but also the invention in respect of which the patent has been granted (section 10, 2004 Act). Whether this will have any practical effect, given the high threshold of "outstanding benefit", remains to be seen. It is also questionable whether such provisions for employee inventions, out of which one cannot contract, have any relevance when so much of modern research is a team effort.

Certain types of threat of patent litigation can give rise to a liability under the 1977 Act which can only be countered by proving the threat to have been justified. This can only be done by bringing and winning the patent action threatened and many solicitors writing letters before action in patent claims have been caught by these provisions. Such provisions impeded the abortive attempts to develop a pre-action protocol for intellectual property.

The 2004 Act goes some way towards relaxing the provisions for patents, while ensuring that the specific evil to which these provisions are directed, that of patentees threatening an alleged infringer's customers, continues to be caught. In addition, it is now specifically stated that it will be possible to make enquiries of anyone for the sole purpose of discovering whether, or by whom, a patent has been infringed, without being regarded as making a threat (section 12, 2004 Act).

Much patent litigation involves applications to amend the patent which is the subject of the litigation, for example, by narrowing the granted claims to exclude prior art that was not considered when the patent was first granted. However such post-grant amendment is at present discretionary even assuming that the patent, as amended, would otherwise be valid. This is in contrast to post-grant opposition proceedings at the European Patent Office (EPO), where the patentee's behaviour in, for example, delaying seeking to amend, is not considered in determining whether a granted patent can be amended in response to an attack on its validity. The situation could arise where different considerations would apply as to the amendment of a patent that is both under opposition at the EPO and is the subject of litigation in England. The 2004 Act removes this anomaly by providing that the considerations that apply in the EPO apply also in the UK (section 2(1) and (5), 2004 Act). As the EPO takes no account of behaviour in determining whether or not allow an amendment, this has the effect of removing this as a consideration in the UK. However the 2004 Act also introduces a new defence, by which the relief available to the patentee for infringement may be restricted where it cannot show that the proceedings in which the amendment took place were brought in good faith.

The 2004 Act seeks to address concerns about the perceived expense of patent litigation with two new provisions: