Subsection 27(4) of the Act provides that the claim must define the invention “distinctly and in explicit terms.” A claim that fails to do so will be invalid for ambiguity . However, as Hughes J has pointed out, the bar for holding a claim invalid for ambiguity is very high – the claim must be essentially incapable of being meaningfully interpreted – and as a consequence, an ambiguity attack is very rarely successful: 2005 FC 1725 -. Nonetheless, Claim 2 of the '551 patent was held to be invalid for ambiguity – apparently for the first time in almost 40 years* (see 2005 FC 1725 , noting that the last time a claim was held invalid on this ground was 1977).
Recall from yesterday’s post that the invention was a security feature for lottery tickets, and Claim 1 was to a ticket comprising a non-play area on the ticket (containing the bar code), “spaced apart from” the play area (containing the prize information or "game data"). This is shown in Fig 3:
Claim 2 was a dependent claim to
2. The printed document of claim 1wherein the game data is printed around the bar code.
This was apparently intended to be illustrated by Fig 4:
It is not possible for the game data to be printed around the bar code at the same time as the play area, which contains the game data, is “spaced apart” from the non-play area, containing the bar code, as is required by the dependency . This means that Fig 4 does not really illustrate Claim 2; while the game data is printed around the bar code, the play area is not spaced apart from the non-play area.
Claim2 was therefore held invalid for ambiguity . This holding of ambiguity is the exception that proves the rule that the bar for a successful ambiguity attack is very high; while the claim was held to be invalid, the claim was internally contradictory, and so was incapable of meaningful interpretation.
*See the comment to this post, noting that Apotex v Hoffman-La Roche (1989), 24 CPR(3d) 289 (FCA) the claims were held invalid for ambiguity, so it has really been 'only' 27 years since the last time an ambiguity attack was successful.