diff --git a/__tests__/spelling-ignore.yml b/__tests__/spelling-ignore.yml
index 09f6463d31..9714e2caff 100755
--- a/__tests__/spelling-ignore.yml
+++ b/__tests__/spelling-ignore.yml
@@ -78,15 +78,26 @@
 - labelable
 - merchantability
 - de-hello
-- 14pt
-- 18pt
 - Helvetica
+- stylesheet
 - DeviceOrientation
 - fieldsets
 - ascii # lowercase needed in reference list
 - CMS
 - dropdown
 
+- 14pt
+- 18pt
+- 32px
+- 2em
+- 10px
+- 24px
+- 8px
+
+# spell checker checks against strict casing & hence some repeated words here
+- Autocomplete
+- Focusable
+
 # Parts of url
 - http
 - https
@@ -206,3 +217,6 @@
 - cantTell
 - TestSubject
 - earl:cantTell
+
+# fns
+- getComputedPriority
diff --git a/_rules/invalid-form-field-value-36b590.md b/_rules/invalid-form-field-value-36b590.md
index aa4e14280d..6ac4301535 100644
--- a/_rules/invalid-form-field-value-36b590.md
+++ b/_rules/invalid-form-field-value-36b590.md
@@ -241,4 +241,4 @@ There are no elements with any of the required [semantic roles][semantic role].
 [required context]: https://www.w3.org/TR/wai-aria/#scope
 [semantic role]: #semantic-role 'Definition of semantic role'
 [text]: https://www.w3.org/TR/WCAG21/#dfn-text
-[visible]: #visible 'Definition of visible'
+[visible]: #visible 'Definition of visible'
\ No newline at end of file
diff --git a/_rules/text-spacing-not-important-b8bb68.md b/_rules/text-spacing-not-important-b8bb68.md
new file mode 100644
index 0000000000..82b94a9da3
--- /dev/null
+++ b/_rules/text-spacing-not-important-b8bb68.md
@@ -0,0 +1,263 @@
+---
+id: b8bb68
+name: Text spacing in `style` attributes is not `!important`
+rule_type: atomic
+description: |
+  This rule checks that the text spacing styles can be adjusted by user, i.e. that `!important` is not applied to the style, unless the style has already exceeded the specified metric for retaining content visibility and functionality.
+accessibility_requirements:
+  wcag21:1.4.12: # Text Spacing (AA)
+    forConformance: true
+    failed: not satisfied
+    passed: further testing needed
+    inapplicable: further testing needed
+input_aspects:
+  - DOM Tree
+  - CSS Styling
+acknowledgments:
+  authors:
+    - Jey Nandakumar
+---
+
+## Applicability
+
+This rule applies to any HTML element that is [visible][], for which one of the following is true:
+
+- the `style` attribute [declares][declared][][word-spacing][] CSS property; or
+- the `style` attribute [declares][declared][][letter-spacing][] CSS property; or
+- the `style` attribute [declares][declared][][line-height][] CSS property.
+
+## Expectation 1
+
+For the test target's [word-spacing][] property, one of the following is true:
+
+- has no [declared][] value; or
+- the [declared][] value specified via the `style` attribute does not have the [important flag][]; or
+- the [computed][] value is at least `0.16` times its [computed][] [font-size][].
+
+## Expectation 2
+
+For the test target's [letter-spacing][] property, one of the following is true:
+
+- has no [declared][] value; or
+- the [declared][] value specified via the `style` attribute does not have the [important flag][]; or
+- the [computed][] value is at least `0.12` times its [computed][] [font-size][].
+
+## Expectation 3
+
+For the test target's [line-height][] property, one of the following is true:
+
+- no [declared][] value; or
+- the [declared][] value specified via the `style` attribute does not have the [important flag][]; or
+- the [computed][] value is at least `1.5` times its [computed][] [font-size][].
+
+## Assumptions
+
+If there is a mechanism available on the page by which text spacing can be adjusted, failing this rule might not mean [success criterion 1.4.12 Text spacing](https://www.w3.org/TR/WCAG21/#text-spacing) is not satisfied.
+
+## Accessibility Support
+
+While some assistive technologies are able to set [user origin][] styles, others, such as browser extensions, are only able to set style with the [author origin][]. Such assistive technologies can not create styles with a high enough [priority][] to override a `style` attribute with the [important flag][]. If accessibility support does not include assistive technologies that override text spacing through [author origin][], this rule should not be used.
+
+## Background
+
+- [Understanding Success Criterion 1.4.12: Text Spacing](https://www.w3.org/WAI/WCAG21/Understanding/text-spacing.html)
+- [CSS Text Module Level 3 - Spacing](https://www.w3.org/TR/css-text-3/#spacing)
+- [CSS Visual formatting model details](https://drafts.csswg.org/css2/visudet.html)
+
+## Test Cases
+
+### Passed
+
+#### Passed Example 1
+
+This `p` element has a `line-height` of `32px` (equals `2em` ) which is above the recommended metric, given the specified font size is 16 pixels.
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<p style="line-height: 32px; !important">
+			The toy brought back fond memories of being lost in the rain forest.
+		</p>
+	</body>
+</html>
+```
+
+#### Passed Example 2
+
+This `div` element has a `letter-spacing` of `0.12em` which is equal to the recommended minimum, given the specified font size is 16 pixels.
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<div style="letter-spacing: 0.12em; !important">
+			The toy brought back fond memories of being lost in the rain forest.
+		</div>
+	</body>
+</html>
+```
+
+#### Passed Example 3
+
+This `strong` element has a `word-spacing` of `1.92pt !important` (equals `0.12em`) which is equal to the recommended minimum, given the specified font size is 16 pixels.
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<strong style="word-spacing: 1.92pt !important;">
+			The toy brought back fond memories of being lost in the rain forest.
+		</strong>
+	</body>
+</html>
+```
+
+### Failed
+
+#### Failed Example 1
+
+This `p` element has a `line-height` of `10px !important` (equals `0.625em` ) which is below the recommended minimum, given the specified font size of the body is 16 pixels.
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<p style="line-height: 30px !important">
+			The toy brought back fond memories of being lost in the rain forest.
+		</p>
+	</body>
+</html>
+```
+
+#### Failed Example 2
+
+This `div` element has a `letter-spacing` of `1.5px !important` (equals `0.09375em`) which is below to the recommended minimum, given the specified font size is 16 pixels.
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<div style="letter-spacing: 1.5px !important;">
+			The toy brought back fond memories of being lost in the rain forest.
+		</div>
+	</body>
+</html>
+```
+
+#### Failed Example 3
+
+This `strong` element has a `word-spacing` of `2.5px !important` (equals `0.15625em` ) which is below the recommended minimum, given the specified font size is 16 pixels.
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<strong style="word-spacing: 8px !important;">
+			The toy brought back fond memories of being lost in the rain forest.
+		</strong>
+	</body>
+</html>
+```
+
+### Inapplicable
+
+#### Inapplicable Example 1
+
+This `p` element is not [visible][] because of `display: none`.
+
+```html
+<p style="display: none">
+	The toy brought back fond memories of being lost in the rain forest.
+</p>
+```
+
+#### Inapplicable Example 2
+
+This text is not [visible][] because it is positioned off screen.
+
+```html
+<p style="position: absolute; top: -999em">
+	The toy brought back fond memories of being lost in the rain forest.
+</p>
+```
+
+#### Inapplicable Example 3
+
+This `body` element does not have a `style` attribute specified.
+
+```html
+<html>
+	<style>
+		body {
+			line-height: 50px;
+		}
+	</style>
+
+	<body>
+		The toy brought back fond memories of being lost in the rain forest.
+	</body>
+</html>
+```
+
+#### Inapplicable Example 4
+
+This `p` element has a [line-height][] of `24px` specified via the style attribute, but does not have the [important flag][].
+
+```html
+<html>
+	<style>
+		body {
+			font-size: 16px;
+		}
+	</style>
+
+	<body>
+		<p style="line-height: 24px;">
+			The toy brought back fond memories of being lost in the rain forest.
+		</p>
+	</body>
+</html>
+```
+
+[visible]: #visible 'Definition of visible'
+[word-spacing]: https://www.w3.org/TR/css-text-3/#word-spacing-property 'CSS Text Module Level 3 - Word Spacing: the word-spacing property'
+[letter-spacing]: https://www.w3.org/TR/css-text-3/#propdef-letter-spacing 'CSS Text Module Level 3 - Tracking: the letter-spacing property'
+[line-height]: https://drafts.csswg.org/css2/visudet.html#propdef-line-height 'CSS Visual formatting model details - line-height property'
+[priority]: https://www.w3.org/TR/cssom/#dom-cssstyledeclaration-getpropertypriority 'CSS Object Model (CSSOM) - Definition getComputedPriority'
+[computed]: https://www.w3.org/TR/css-cascade-3/#computed-value 'CSS Cascading and Inheritance Level 3 - Computed Values'
+[author origin]: https://drafts.csswg.org/css-cascade-4/#cascade-origin-author 'CSS Cascading and Inheritance Level 4 - Cascading Origins - Author Origin'
+[user origin]: https://drafts.csswg.org/css-cascade-4/#cascade-origin-user 'CSS Cascading and Inheritance Level 4 - Cascading Origins - User Origin'
+[font-size]: https://www.w3.org/TR/css-fonts-3/#propdef-font-size 'CSS Fonts Module Level 3- Font size: the font-size property'
+[important flag]: https://www.w3.org/TR/cssom/#css-declaration-important-flag 'CSS Object Model (CSSOM) - important flag'
+[declared]: https://www.w3.org/TR/css-cascade-3/#declared 'CSS Cascading and Inheritance Level 3 - Declared Values'