In 2002 I found myself in the unfortunate position of having to justify the legality of carrying my Leatherman Wave.

Hunting around on the web, the apparently "canonical" page, linked to/associated with has some information, but it's less than complete.

It quotes 269MGL10(b), which (among other things) construes the carriage of a "knife having a blade of over one and one-half inches" as "punishable by imprisonment". For reference, my Leatherman Wave's blade measures 2 5/8", and a plastic cutlery knife measured 2 1/8".

It goes on to assert that:

  Massachusetts Case Law:
- "Knives described as 'kitchen knife,' 'folding type knife,'
   and 'Swiss army knife' may not fall within category of
   dangerous weapons." (1994)

But the citation leaves much to be desired. Further research indicates that this is a reference to a 1994 Appeals Court of Massachusettts decision, Commonwealth v. Timothy Henry (93-P-969). This case seems like not the best of precedents, since the defendant is found guilty of rape. Nonetheless, he was not found guilty of "aggravated rape" because the knife he was carrying did not constitute a 269MGL10(b) "dangerous weapon", by virtue of being classified as a "kitchen knife," "folding type knife" or "Swiss army knife." Specifically, to quote Footnote 7:

7 The aggravated rape statute also provides that the "aggravation" of a rape may occur when the offense of carrying a dangerous weapon, described in G. L. c. 269, ' 10(b) is committed or attempted. Because the knives found in the defendant's bedroom were classified as "kitchen knife" and "folding type knife" or a Swiss Army knife, they may not fall within the category of "dangerous weapons" described in G. L. c. 269, ' 10(b). In any event, the Commonwealth did not pursue this course as the means of proving the "aggravation" at trial.

This is not as definitive as I would have liked. Browsing around, we find in the LEXIS/NEXIS commentary:

 Purpose of GL c 269 ' 10(b) is to outlaw carrying of those knives
 which are primarily designed for stabbing human beings or for other
 unlawful objectives. Commonwealth v Miller (1986) 22 Mass App 694,
 497 NE2d 29.
 Knives described as "kitchen knife," "folding type knife" and "Swiss
 army knife" may not fall within category of "dangerous weapons."
 Commonwealth v Henry (1994) 37 Mass App 429, 640 NE2d 503.

I have not been able to easily find the full text of Miller.