10.5 Evaluating credibility of sources

Types of Legal Sources

Legal sources are the raw materials of legal research and writing. Knowing how to categorize them helps you determine how much weight each source carries in a legal argument.

Primary vs. Secondary Sources

Primary sources are the law itself, created by government bodies with lawmaking authority. These include constitutions, statutes, regulations, and court decisions. Because they are the law, primary sources carry the most weight in legal arguments.

Secondary sources explain, analyze, or comment on primary sources. Examples include legal treatises, law review articles, restatements, and legal encyclopedias. They're useful for understanding complex areas of law and finding relevant primary sources, but they don't have the force of law themselves.

Binding vs. Persuasive Authority

Not all primary sources carry equal weight. The key distinction is whether a source is binding or persuasive in a given situation.

• Binding authority must be followed by a court. This includes the jurisdiction's own constitution, statutes, and decisions from higher courts in the same jurisdiction.
• Persuasive authority can influence a court but doesn't have to be followed. This includes decisions from other jurisdictions, lower court opinions, dissenting opinions, and secondary sources.

The strength of persuasive authority depends on factors like the reputation of the issuing court, the quality of its reasoning, and how factually similar the case is to yours.

Hierarchy of Legal Authority

Legal authority follows a clear hierarchy:

1. Constitutional law sits at the top, superseding all other forms of law
2. Federal statutes take precedence over state laws in areas of federal jurisdiction
3. Statutes enacted by legislatures generally override common law (judge-made law)
4. Higher court decisions bind lower courts within the same jurisdiction
5. Executive orders and administrative regulations must comply with both statutory and constitutional law

Understanding this hierarchy is essential for determining which source controls when authorities conflict.

Factors Affecting Credibility

When you find a legal source, you need to assess how much trust to place in it. Several factors help you make that judgment.

Source Reputation

• Established legal publishers (West, LexisNexis) maintain rigorous editorial standards, making their publications generally reliable
• Government websites (.gov domains) offer official versions of statutes and regulations
• Publications from reputable law schools and bar associations tend to be high quality
• A source's track record for accuracy and its recognition within the legal community are good indicators of reliability

Author Expertise

The credibility of a source often depends on who wrote it. Look for:

• Advanced law degrees (JD, LLM, SJD)
• Significant practice experience in the relevant area of law
• Judicial experience or a record of legal scholarship
• A history of publications in reputable legal journals

You can verify expertise by reviewing the author's credentials, publication record, and professional background.

Publication Date

Currency matters in law because statutes get amended, cases get overruled, and regulations change.

• Recent publications are generally more credible for current legal issues
• Older sources can still be valuable for historical context or tracing the development of legal doctrine
• In fast-moving areas like technology or healthcare law, recency carries extra weight
• Regular updates or new editions signal that a source is being maintained for accuracy

Peer Review Process

Peer-reviewed legal journals subject articles to expert scrutiny before publication, which helps catch errors, weak reasoning, and unsupported claims. Law reviews from top-tier law schools typically employ rigorous review processes. Information about a journal's review process is usually available in its editorial policies.

Peer-reviewed sources generally carry more weight than non-reviewed publications in academic and legal circles.

Citation Frequency

How often a source is cited by courts and other scholars can signal its influence and acceptance.

• Citator tools like Westlaw's KeyCite and LexisNexis's Shepard's Citations track how often a source is referenced
• High citation frequency suggests a source is considered authoritative on a particular issue
• Recent citations are more valuable than older ones for assessing current relevance
• Citation patterns can also reveal how legal thinking on a topic has evolved over time

Evaluating Online Sources

Online research gives you fast access to a huge volume of legal information, but not all of it is equally reliable. You need a framework for evaluating digital sources.

Official vs. Unofficial Websites

• Official government websites (.gov) provide authoritative versions of statutes, regulations, and court opinions
• State bar association websites often offer reliable resources and ethics opinions
• Unofficial websites may provide useful commentary but should always be cross-referenced with official sources
• Legal research platforms (Westlaw, LexisNexis) offer both official and unofficial content and clearly distinguish between them

Domain Extensions

Domain extensions give you a quick initial signal about a source's nature:

• .gov indicates an official government website, typically the most authoritative for legal texts
• .edu belongs to educational institutions, often hosting law school publications and databases
• .org is used by non-profit organizations, including many reputable legal associations
• .com covers commercial publishers and law firm websites, requiring more careful evaluation
• Country-specific extensions (.uk, .ca, .au) are useful for foreign and comparative law research

Currency of Information

• Check for "last updated" dates on web pages
• Be cautious of outdated legal information, especially in rapidly changing fields
• Verify that online statutes and regulations reflect the most recent amendments
• Use legal news sources and blogs to stay current, but always confirm their claims against primary sources

Cross-Referencing with Print Sources

• Compare online legal information with reputable print sources to verify accuracy
• Consult print versions of official codes and reporters when authoritative citations are required
• Print sources can offer historical perspective not always available in online databases
• Cross-referencing helps catch errors or omissions in online legal content

Assessing Case Law

Evaluating judicial decisions requires attention to several factors that determine how much authority a case carries.

Court Hierarchy

The level of the court that issued a decision directly affects its weight:

• Supreme Court decisions (federal or state) bind all lower courts within that system
• Federal Circuit Court decisions are binding within their respective circuits
• State supreme court decisions bind all lower state courts
• Trial court decisions generally have limited precedential value

Precedential Value

Not all opinions from the same court carry equal weight:

• Published opinions typically carry more precedential weight than unpublished ones
• En banc decisions (where the full court sits) generally outweigh panel decisions
• Majority opinions set binding precedent; concurring and dissenting opinions may offer persuasive reasoning but don't create precedent
• The breadth or narrowness of a court's holding affects how broadly it applies to future cases
• Clear, well-reasoned opinions tend to carry more persuasive force

Age of Decision

• Recent decisions are generally more relevant, especially in evolving areas of law
• Older cases may still be authoritative if they haven't been overruled or superseded
• Always consider whether subsequent legal developments have undermined an older decision
• Historical cases can provide important context for understanding how legal principles developed

Subsequent Treatment

This is one of the most critical steps in evaluating case law:

1. Shepardize or KeyCite every case you plan to rely on
2. Check whether the case has been overruled or abrogated, which destroys its precedential value
3. Look for positive treatment (followed, cited approvingly), which strengthens the case's authority
4. Watch for negative treatment (criticized, distinguished, questioned), which may weaken it
5. Check whether subsequent legislation has affected the case's continued validity

Analyzing Secondary Sources

Secondary sources provide context, analysis, and synthesis of primary law. They're especially useful early in your research, but you need to evaluate their quality carefully.

Author Credentials

• Educational background, including law degrees and specializations
• Professional experience such as years of practice or judicial service
• Publication history in reputable legal journals
• Academic positions or affiliations with respected legal institutions
• Recognition in the legal community through awards, citations, or expert testimony

Publisher Reputation

Established legal publishers (West, LexisNexis, Oxford University Press) generally produce high-quality secondary sources. University presses associated with top law schools and professional organizations like the American Bar Association and the Practising Law Institute also produce reliable materials.

Be cautious of self-published legal publications, which may lack rigorous editorial review.

Scope of Coverage

• Does the source provide a comprehensive overview or focus on specific aspects of a topic?
• Does it address the jurisdictions and legal systems relevant to your research?
• Does it engage with conflicting views and emerging issues, or present only one perspective?
• Does it include practical applications or theoretical discussions appropriate to your purpose?

Currency of Information

• Check the publication date to confirm the information reflects current law
• Look for sources with regular updates or new editions
• In fast-changing fields, supplement older authoritative texts with recent articles or supplements
• Evaluate whether the source addresses recent landmark cases or legislative changes

Verifying Statutory Sources

Statutory research requires careful verification to ensure you're relying on current, authoritative law.

Official vs. Unofficial Codifications

Official codifications are published by government entities and carry the force of law. Unofficial codifications (annotated codes) are published by commercial publishers and add editorial enhancements like case annotations and cross-references.

Unofficial codes are often more useful for research because of these added features, but you should always verify critical statutory language against the official code before relying on it in legal writing.

Currency of Statutes

• Check the effective date to confirm the statute is currently in force
• Be aware of pending legislation that may affect existing statutes
• Use statutory supplements or online updates to access the most recent amendments
• Watch for sunset provisions that automatically terminate a statute after a specified date
• Make sure you're working with the version of the statute applicable to your specific legal issue

Legislative History

Legislative history can help you understand what a legislature intended when it enacted a statute. Key sources include:

• Committee reports, which often contain the most authoritative statements of legislative intent
• Floor debates and hearing transcripts
• Statements by bill sponsors or key legislators
• Prior versions of the bill, which show changes made during the legislative process

Be cautious about overreliance on legislative history. Courts vary significantly in how much weight they give it, with some (particularly textualist judges) preferring to rely on the statutory text alone.

Annotations and Commentary

• Case annotations show how courts have interpreted and applied the statute
• Scholarly commentary offers insights into potential interpretations and applications
• Cross-references connect you to related statutes, regulations, or constitutional provisions
• Practice notes provide practical guidance on statutory application

Remember that annotations and commentary are secondary sources. They don't carry the force of law.

Critiquing Scholarly Articles

Legal scholarship can provide cutting-edge analysis and novel arguments, but you need to evaluate it critically.

Journal Reputation

• Consider the ranking and impact factor of the law review or journal
• Journals associated with top-tier law schools or respected legal organizations tend to carry more weight
• Evaluate the journal's peer review process and editorial standards
• Check whether the journal is widely cited by courts and other scholars
• Note whether the journal specializes in a particular area of law relevant to your research

Author Qualifications

• Academic credentials, including advanced degrees in law or related fields
• Professional experience such as legal practice or judicial clerkships
• Publication history and recognized areas of expertise
• Standing in the legal community (speaking engagements, expert testimony)
• Any potential biases or conflicts of interest that may influence the author's perspective

Methodology

A strong scholarly article should demonstrate:

• Sound research methods supporting its arguments
• Breadth and depth in its use of primary and secondary sources
• Logical structure and coherent argumentation
• Clear explanations of legal concepts and thorough analysis of relevant case law
• Engagement with potential counterarguments and acknowledgment of limitations

Citation Quality

• Examine the quantity and quality of citations to primary legal sources
• Evaluate the use of secondary sources, including other scholarly articles and treatises
• Check for proper citation format according to legal citation standards (typically the Bluebook)
• Look for an appropriate balance between recent and historical sources
• Assess whether the citations actually support the claims being made

Evaluating Practitioner Materials

Practitioner materials bridge the gap between academic legal theory and real-world practice. They're valuable for understanding how the law works on the ground.

Author Experience

• Years of practice in the relevant area of law
• Specialization or recognized expertise in specific legal niches
• Reputation among peers and within the legal community
• Involvement in landmark cases or significant legal developments
• Bar association leadership roles or committee memberships

Publisher Reputation

Publishers like the American Bar Association and the Practising Law Institute are known for producing high-quality, practice-oriented materials. Evaluate the publisher's history of accuracy, editorial processes, and whether it specializes in particular areas of law.

Frequency of Updates

• How often is the material updated or revised?
• Does it use loose-leaf services or online platforms that offer real-time updates?
• Does the update frequency match the pace of change in the relevant area of law?
• Do updates cover recent case law and statutory changes comprehensively?

Practical Applicability

The best practitioner materials provide actionable guidance:

• Practice tips, checklists, and sample documents or forms
• Coverage of procedural aspects and practical challenges
• Discussion of common client concerns and frequently encountered issues
• Treatment of ethical considerations and professional responsibility

Assessing International Sources

As legal issues become more global, you may need to evaluate sources from foreign jurisdictions. This requires additional care.

Authenticity of Translations

• Verify that translations come from reputable sources or official translators
• Consider using multiple translations to cross-check accuracy and nuance
• Be aware that legal terms often don't translate directly between languages; a literal translation may miss important legal meaning
• Look for explanatory notes addressing translation challenges
• For critical documents, consider consulting with native speakers or language experts

Official vs. Unofficial Versions

• Identify official publications of foreign laws, treaties, and court decisions
• Be cautious of unofficial compilations or translations that may contain errors
• Use government websites or official legal databases of foreign jurisdictions when possible
• Look for disclaimers regarding the official status of international legal materials

Jurisdiction Relevance

• Assess whether the international source actually applies to your legal issue
• Consider differences in legal systems (common law vs. civil law) when evaluating foreign sources
• Understand the court hierarchy and precedent rules in the relevant foreign jurisdiction
• Evaluate the persuasive value of international sources in domestic legal arguments
• Consider whether treaties or agreements affect the source's relevance

Currency of Information

• Check publication dates and effective dates of foreign laws and regulations
• Be aware of recent political or legal developments that may affect older sources' validity
• Look for updates or amendments to international treaties and conventions
• Use international legal news sources to stay informed of changes in foreign jurisdictions

Tools for Source Evaluation

Several tools can help you evaluate legal sources more efficiently and systematically.

Citators

Shepard's Citations (LexisNexis) and KeyCite (Westlaw) are the two primary citator services. They allow you to:

• Track the subsequent history and current status of cases and statutes
• See how often and in what context a source has been cited
• Identify negative treatment (overruled, criticized, distinguished) that may undermine a source's authority
• Check the recency and relevance of citing sources

Always citator-check any authority you plan to rely on in legal writing.

Legal Research Databases

• Westlaw, LexisNexis, and Bloomberg Law offer advanced search and filtering capabilities
• Use database features to narrow results by jurisdiction, date range, and source type
• Take advantage of headnotes and topic classification systems to identify relevant legal principles
• Use "similar document" or "related content" features to expand your research efficiently

Peer Review Indicators

• Look for clear statements about the peer review process in journal policies or article metadata
• Consider the composition and expertise of the editorial board
• Be aware of different types of peer review (double-blind, single-blind, open) and what each means for quality assurance
• Post-publication peer review mechanisms, such as online commentary or response articles, can also signal a source's reception

Impact Factor Metrics

Journal impact factors measure how frequently a journal's articles are cited, providing a rough quantitative gauge of influence. However, they have limitations:

• Impact factors may not accurately reflect quality in niche or emerging legal fields
• Alternative metrics (altmetrics) capture online engagement and social media mentions
• Subject-specific rankings may be more relevant for specialized legal topics
• Quantitative metrics should be balanced with qualitative assessment of the source's actual reasoning and analysis