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Industry research
Read time4 min readUpdatedDecember 2025

ATS: How They Actually Work

How ATS platforms store and surface candidates, and where human review shapes outcomes.

The Reality

Selection Procedure

Automated hiring tools are treated as selection procedures, which triggers requirements around job-relatedness and adverse impact. Automation varies widely and often complements human review rather than replacing it.123

Source
EEOC guidance on software, algorithms, and AI

Decision Rights Map

ATS platforms store and route information, while screening logic and human review can both shape outcomes. This map shows where automation is possible, not guaranteed.12

Decision rights hierarchy
1
Data Layer

ATS Infrastructure

Parsing, storage, search, workflow routing

2
Logic Layer

Screening Automation

Eligibility rules, assessments, ranking

3
Decision Layer

Human Judgment

Shortlist, interview selection, final hire

Humans decide

The ATS organizes—humans choose. Understanding this hierarchy explains what you can and can't optimize for.

Fig. 1 — Decision RightsWhere automation operates vs where humans decide

What an ATS actually does

Most ATS systems function as workflow engines. They store candidate data, support filtering, and enable recruiters to search. Automation can sit on top of this workflow, but it is not uniform across employers or tools.124

Eligibility Filters

Explicit eligibility rules like work authorization or required credentials can filter candidates before review.12

Search & Discovery

Recruiters use filters and keyword search to surface candidates from the database.12

Why the auto-reject myth persists

ATS workflows can feel opaque, so candidates assume resumes are automatically rejected. The evidence we have shows ATS platforms are primarily workflow systems with varying levels of automation. Human review still matters, but the rules and models used can shape who gets seen first.123

Definition: selection procedures

A selection procedure is any tool or process that influences who advances in hiring. Under EEOC guidance, software and algorithms can fall under this definition, which raises obligations around job-relatedness and adverse impact.1

Practical takeaways

  • •Use standard section headers so both parsers and humans can navigate quickly.
  • •Write role titles and core skills in plain language, not internal jargon.
  • •Avoid graphics or tables that disrupt parsing and readability.

FAQ

Do ATS systems automatically reject resumes?

Automation varies. Some tools apply eligibility rules, but many systems are primarily workflow engines with humans making final choices.

Is keyword stuffing useful?

No. Over-optimized keyword blocks can reduce clarity for humans and can be flagged by screening logic.

What is the best ATS-safe format?

A single-column layout with clear headings, consistent dates, and standard section names is the safest baseline.

How we optimize for this

01

Clarity over Keywords

We focus on clear, standard language so both the parser AND the human understand you.

02

No "Beat the Bot" Tricks

We don't sell fear. We sell standard, readable formatting.

Related Research

Human vs. AlgorithmAIAutomation and BiasResearchHow Recruiters ReadResearch

Sources

  1. Select Issues: Assessing Adverse Impact in Software, Algorithms, and AI Used in Employment Selection Procedures - EEOC (2023).
  2. An Auditing Imperative for Automated Hiring Systems - Harvard Journal of Law & Technology (2021).
  3. Data-Driven Discrimination at Work - North Carolina Journal of Law & Technology (2017).
  4. The Ethics of AI in Recruiting - Journal of Business Ethics (2022).

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