TLDR, during a 1983 survey of 728 officers and 479 police spouses, “Approximately, 40 percent [of the officers] said that in the last six months prior to the survey they had behaved violently towards their spouse or children.” Also, “Ten percent of the spouses reported being physically abused by their mates at least once; the same percentage claim that their children were physically abused.”
You recall incorrectly. The 40% does in fact refer specifically to the officers. You are correct about the definition of violence being vague though, which is why I included the second quotation in my TLDR. The rate of physical violence was around 10% according to the spouses of the officers, with the other 30% apparently consisting of verbal abuse and threatening but non-physical behavior.
The actual document transcribing the hearing I quoted from is here: https://files.eric.ed.gov/fulltext/ED338997.pdf For convenience I will be referencing the page numbers in the pdf file and at the bottoms of pages, not the original numbers at the tops of pages (which are five behind). Dr. Leanor Boulin Johnson’s part of the hearing begins near the end of page 37, and she addresses congress for two and half pages. Then in pages 41-53 her prepared statement is included.
In her oral statement, she said the following (page 39) :
The written report says the same thing, with a bit of elaboration (page 47):