How to edit " Obama has just broken the, up 'til now, structural constraint"?

The meaning of the sentence is clear, but it looks rather awkward, especially the form "broken the" - it sounds meaningless until you read through the sentence.
Is it a grammatical mistake? How to make it better?

Context:

Sociology: Structural constraints?
What would be a good definition of a structual constraint having to do with Sociological terms?

Best Answer - Chosen by Asker
A structural constraint is the level of restriction placed on your options by your social role(functionalist perspective) or by your lack of access to social, cultural, economic or political resources (conflict perspective) eg
(i) Obama has just broken the, up 'til now, structural constraint that only white men achieve the position of USA president
(ii) An over 70s applicant would have little chance of being accepted for the job of a fashion model.
(iii) non heterosexual partners have difficulty accessing rights accorded to heterosexual couples

nb it's important in using the concept of 'structural constraint' to avoid sociological determinisim. This has been explained well in the excellent article referenced below. This is the relevant extract from that article:

The "society argument" often arises in response to critiques of the above styles (individual' free choice) of argumentation, and tends to appear in a form such as: "Society made me do it." Students often think that this is a good sociological argument, since it uses society as the basis for explanation. However, the problem is that the use of the broad concept "society" masks the real workings of the situation, making it next to impossible to build a strong case. This is an example of reification, which is when we turn processes into things. Society is really a process, made up of ongoing interactions at multiple levels of size and complexity, and to turn it into a monolithic thing is to lose all that complexity. People make decisions and choices. Some groups and individuals benefit, while others do not. Identifying these intermediate levels is the basis of sociological analysis.
Source(s):
http://www.unc.edu/depts/wcweb/handouts/…

this is the very good, concise 'Handout on Sociology' produced by University of North Carolina

More:
http://answers.yahoo.com/question/index?qid=20090404174538AAKGPfL