through the cracks

through the cracks

Going unnoticed, undealt with, neglected, or ignored, especially in a corporate, political, or social system. Used especially after the verbs "slip" and "fall." With other issues like drug addiction and unemployment taking priority for the government, the welfare of these vulnerable children often slips through the cracks. We were all so busy drawing up the contracts for this new deal that the thank-you dinner we'd promised our interns simply fell through the cracks.
See also: crack, through
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

*through the cracks

Fig. [moving] past the elements that are intended to catch or detect such things. (*Typically: fall ~; drop ~; go ~; slip ~.) I am afraid that some of these issues will slip through the cracks unless we make a note about each one.
See also: crack, through
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
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References in classic literature ?
Humans do this very thing, and some of them call it "free will." Cocky, staring at the open door, was in just the stage of determining whether or not he should more closely inspect that crack of exit to the wider world, which inspection, in turn, would determine whether or not he should venture out through the crack, when his eyes beheld the eyes of the second discoverer staring in.
The presence of microcracks provides high durability of this material because the transport of environmental products into the concrete takes place through the cracks with a width above 0.1 mm [3].