IANAL but that's why law has to be interpreted by judges rather than being a book of absolute rules.

Lots of codified laws are bent or modified by prevailing social attitudes, customs or precedent, so you could argue "I looked at it a couple of years ago and then independently decided to implement something similar" is a very different situation to "we read through the code and a week later started on a competitor".

Whether you'd get away with it is another matter, depending upon interpretation and perspective.