[3] He formed a company named Dentcom which in late 1982 began to develop a program in a different computer language (BASIC) but with very similar functionality called Dentlab, marketed as a Dentalab successor.

On 30 June 1983 Jaslow's company filed a suit in Pennsylvania state court alleging that Whelan had misappropriated its trade secrets.

[8] Structure, sequence and organization (SSO) in this case was defined as "the manner in which the program operates, controls and regulates the computer in receiving, assembling, calculating, retaining, correlating, and producing useful information.

An ad hoc judgement based on careful comparison of the works would be needed to determine where in this spectrum any alleged copying lay, and to decide whether it was at a sufficiently specific level to be a violation rather than a different expression of the same idea.

[12] The court rejected the "extrinsic-intrinsic" test that had commonly been used until then, where an expert and a lay observer are asked to independently determine whether the works are substantially similar.

[13] The court found that the Copyright Act of 1976 supported its view of a software work as a compilation[fn 1], saying:[14] Although the Code does not use the terms "sequence," "order," or "structure," it is clear from the definition of compilations and derivative works, and the protection afforded them, that Congress was aware of the fact that the sequencing and ordering of materials could be copyrighted, i.e. that the sequence and order could be parts of the expression, not the idea, of a work.The Whelan decision initiated a period of excessively tight protection, suppressing innovation, since almost everything other than the broad purpose of a software work would be protected.

[2] Later the same year, in Broderbund v. Unison the court cited Whelan when finding that the overall structure, sequencing, and arrangement of screens, or the "total concept and feel", could be protected by copyright.