A rule with no real peer group
Unlike most states covered on this site, South Dakota doesn't belong to a meaningful peer group for its negligence rule. Multiple independent legal sources describe it as the only state in the nation currently using a slight/gross negligence standard — there simply isn't another state to meaningfully compare it to on this specific point.
Not even South Dakota's neighbors share it
North Dakota, Minnesota, Iowa, and Nebraska — every state bordering South Dakota — all use an ordinary percentage-based modified comparative negligence system, with either a 50% or 51% bar. None of them ask whether a plaintiff's fault was qualitatively "slight"; they all simply compare a fault percentage against a fixed threshold.
A real 2015 attempt to change this
South Dakota's legislature has, at least once, considered moving away from this unique standard. A 2015 bill proposed amending SDCL § 20-9-2 to replace its "slight in comparison with" language with "less than" the defendant's negligence — a change that would have shifted South Dakota toward an ordinary percentage-based comparative system, more in line with its neighbors. The bill also addressed a specific court decision, Wood v. City of Crooks, by proposing that a jury's percentage finding not be disclosed in a way that let courts rule on "slightness" as a matter of law.
The slight/gross standard, still standing
Despite that 2015 effort, more recent legal sources continue to describe South Dakota's operative standard as "slight in comparison with" the defendant's negligence — the original, nationally unique language. Whatever became of that specific bill, South Dakota's practical standard today remains the one courts have applied for decades, not a percentage-based alternative.
Why this genuine isolation matters
Someone moving between South Dakota and virtually any neighboring state encounters something more than just a different percentage cutoff within a familiar framework — they encounter a genuinely different kind of question altogether. See our full guide to how fault is actually assessed under this standard for how South Dakota courts have approached that question in practice.