What Is Redaction and Why a Black Highlight Isn't Enough

The redaction disaster

In 2016, the NYPD released "redacted" body camera footage to the public. The sensitive parts were covered with black rectangles. Looked official enough.

Except someone discovered that the black rectangles could simply be dragged aside, revealing everything underneath. The "redaction" was just a black highlight drawn on top: cosmetic, not permanent.

This kind of mistake happens more than you'd think.

Cosmetic vs. permanent redaction

There are two ways to "hide" text in a PDF:

• Cosmetic (wrong): Drawing a black rectangle over the text. The text is still there, just covered. Anyone with a PDF editor can remove the rectangle and read the original text. Copy-pasting the surrounding area also captures the "hidden" text.
• Permanent (right): Actually removing the text from the PDF and replacing it with a blank area or a redaction mark. The original text is gone, for good.

Why this matters

Improper redaction has caused real damage:

• Legal cases. Courts have sanctioned lawyers for releasing documents with improper redaction, exposing witness names and evidence.
• Government documents. FOIA releases with cosmetic redaction have exposed personal information of citizens.
• Corporate disclosures. Companies have accidentally released financial data, trade secrets, and personal employee information.

The common thread: someone used a highlight tool instead of a proper redaction tool.

How proper redaction works

True redaction in a PDF involves:

1. Identifying the text or area to redact
2. Removing the underlying content from the PDF structure
3. Placing a visible mark (usually a black rectangle or "[REDACTED]" text) in its place
4. Flattening the page so the redaction mark can't be edited or removed

After proper redaction, the original text is gone. Not hidden. Gone.

How to redact properly

TabTasker's Redact PDF tool performs proper redaction:

1. Open your PDF
2. Draw rectangles over the areas you want to redact
3. Apply the redaction, and the tool removes the underlying content and flattens the page
4. Download the permanently redacted PDF

The redaction happens locally in your browser. Your document never leaves your device.

Red flags to watch for

• If a tool calls it "highlighting" or "covering" instead of "redaction," it's probably cosmetic.
• If you can still select and copy text under the black mark, it's not real redaction.
• If the tool doesn't mention "flattening" or "removing content," be skeptical.

Bottom line

If you're sharing a document with sensitive information, make sure the redaction is real. A black highlight isn't redaction. It's a sticker. And stickers can be peeled off.

Real-world redaction failures and what they taught us

The NYPD case is not isolated. Redaction failures occur regularly across government, legal, and corporate settings. A few notable examples:

• The US Department of Justice released court documents where sensitive text was "redacted" using a black font colour on a black background. It wasn't an image overlay, but literally text set to a black colour. Selecting all and changing the font colour revealed the content.
• A major law firm submitted court filings with black rectangles over witness names. The rectangles were drawn as PDF annotation objects, not flattened, which meant anyone with a PDF editor could delete the annotation layer and read the names.
• Government FOIA releases have repeatedly exposed personal information when staff used presentation software or Word to draw shapes over text, not understanding that the underlying text remained selectable.

The pattern in every case is the same: the redaction was visual, not structural.

How to verify your redaction worked

Before sharing a redacted document, test it yourself:

• Try to select and copy text from the redacted area. If you can, it is not properly redacted.
• Open the file in a different PDF viewer to see if the redaction marks behave consistently.
• Check the document metadata. Some tools leave the original text in the document's text extraction layer even after visual redaction.
• Search the document for a known redacted word. If the search finds it, the text is still present in the document structure.

TabTasker's Redact tool performs proper structural redaction by removing content from the PDF and flattening the page. After redaction, the text is genuinely gone. It can't be found by search, selection, or metadata extraction. Once the page content is clean, pair it with the PDF Metadata cleaner to strip author names and edit history, then encrypt the file before sharing.