In legal writing, shorter is generally better. One way to tighten up your briefs, and to avoid information overload, is to include only the details that are material to your theory of the case. Omitting irrelevant details has the added benefit of allowing the reader to focus on the relevant ones: the reader isn’t forced to devote mental energy to sifting through the facts to determine which details are relevant and which aren’t.
The relevance of a particular detail depends on what’s at issue. Sometimes, a detail’s relevance is obvious. For example, if the issue is whether a personal injury claim arising from a car accident is barred by the statute of limitations, the date of the accident and the date the complaint was filed are relevant details. A detail’s irrelevance may also be fairly obvious. For example, in a pedestrian knockdown case involving a driver who swerved to avoid a dog that suddenly darted into the road, it is difficult to imagine a situation in which the dog’s breed is relevant to either party.
Some details, while not critical, are relevant because they help paint a picture of the parties or events at issue. For example, while liability in a dog bite case doesn’t turn on the dog’s breed, the plaintiff will more likely mention the breed if the dog is a pit bull or rottweiler than if it’s a similarly-sized labrador retriever or standard poodle.
Although precise dates may be material (as in the statute of limitations example above), frequently they are not. For example, regardless of whether your case involves a substantive or procedural issue, the exact dates of most litigation-related events—assuming you must mention them in the first place—are often irrelevant; even the exact date the complaint was filed is irrelevant in most cases. The exact dates of some of the events underlying the action may be irrelevant as well. In these circumstances, specifying a month and year will generally suffice.
Finally, a warning: your brief must include all relevant details, including ones that favor the other party. If you omit a relevant detail, you will lose your credibility with the court.