Copyright, Designs and Patents Act 1988, section 50B

Decompilation

Part I Copyright

(1)It is not an infringement of copyright for a lawful user of a copy of a computer program expressed in a low level language—

(a)to convert it into a version expressed in a higher level language, or

(b)incidentally in the course of so converting the program, to copy it,

(that is, to “decompile” it), provided that the conditions in subsection (2) are met.

(2)The conditions are that—

(a) it is necessary to decompile the program to obtain the information necessary to create an independent program which can be operated with the program decompiled or with another program (“the permitted objective”); and

(b)the information so obtained is not used for any purpose other than the permitted objective.

(3)In particular, the conditions in subsection (2) are not met if the lawful user—

(a)has readily available to him the information necessary to achieve the permitted objective;

(b)does not confine the decompiling to such acts as are necessary to achieve the permitted objective;

(c)supplies the information obtained by the decompiling to any person to whom it is not necessary to supply it in order to achieve the permitted objective; or

(d)uses the information to create a program which is substantially similar in its expression to the program decompiled or to do any act restricted by copyright.

(4)Where an act is permitted under this section, it is irrelevant whether or not there exists any term or condition in an agreement which purports to prohibit or restrict the act (such terms being, by virtue of section 296A, void).

Definitions used in section 50B 1

copy

(1)The copying of the work is an act restricted by the copyright in every description of copyright work; and references in this Part to copying and copies shall be construed as follows.

Defined in s.17(1) · see it in the full Act

Cases considering section 50B 4

IBM United Kingdom Limited v LzLabs GmbH & Ors

[2025] EWHC 532 (TCC) · 10 March 2025Limits

Permits decompilation for interoperability only where the statutory conditions are met, including necessity and use of the information only for the permitted objective. The court applied the equivalent Article 6 analysis and found the conditions unmet. (see paras [237]-[240], [341]-[345])

IBM UNITED KINGDOM LIMITED v LZLABS GmbH & Ors

[2022] EWHC 2094 (TCC) · 5 August 2022Interprets

The court treated Section 50B as permitting study and testing of computer programs for defined purposes. That informed the argument that reverse engineering might not breach the agreement, subject to the separate effect of Section 296A (see paras [32], [51]-[55]).

Take-Two Interactive Software Inc & Anor v James & Ors

[2020] EWHC 179 (Pat) · 29 January 2020Limits

The court considered the decompilation defence and held that it would not answer the independent finding of authorised copying, even if the defence were otherwise available. The court found that the evidence did not describe decompilation as converting a program from low-level to higher-level language. The requirements of section 50B(1) were therefore not met.

What each judgment says about section 50B is in the case-law panel in the full Act.

Amendments and notes

1 notes from legislation.gov.uk

Amendments

  1. F184Ss. 50A-50C inserted (1.1.1993) by S.I. 1992/3233, reg.8.