Moffitt’s Developmental Taxonomy & the Age–Crime Curve

Criminal Careers Approach: Core Ideas

• Purpose: Explains variability in criminal behaviour across individuals and over time.
• International longitudinal studies consistently show:
  • Surge in offending from $7\text{–}17$ years.
  • Prevalence halves by the early 20s: $P<em>{20s} \approx \frac{1}{2} P</em>{teens}$.
  • By the late 20s, near-total desistance (the vast majority have stopped offending).
• Most desistance is spontaneous—people “age out” of crime without external intervention.
• Implication: Any theory of crime must accommodate both
  1. Stable, long-term individual differences.
  2. Dramatic age-related changes in prevalence.

The Age–Crime Curve

• A robust empirical regularity observed across many countries (shape can vary slightly but general form holds).
• Visual pattern: Low childhood offending → rapid teenage spike → steep decline in early adulthood → plateau near zero by late 20s.
• Aggregate curve masks heterogeneous individual trajectories.

Moffitt’s Developmental Taxonomy (1993)

• Proposes two primary trajectories within the age–crime curve to reconcile individual stability with population-level change.
• Solves two “paradoxes”:
  1. Continuity – Some individuals show stable antisocial behaviour across the life span.
  2. Change – Overall crime rates rise and fall sharply with age.
• Uses a typological lens: different groups, different etiologies, different policy needs.

1. Life-Course Persistent (LCP) Offenders

• Small proportion of the population.
• Characteristics:
  • Early onset (often in childhood, before adolescence).
  • Offending persists into adolescence, adulthood, and sometimes throughout life.
  • Tend to commit a higher volume and wider variety of offences.
• Etiological factors (as proposed by Moffitt – only briefly mentioned in transcript):
  • Neuropsychological deficits.
  • Adverse family environments.
  • Cumulative continuity: early problems cascade, creating entrenched patterns.
• Policy implication: Require intensive, long-term support and tailored interventions.

2. Adolescent-Limited (AL) Offenders

• Numerically large group; dominates teenage crime spike.
• Traits:
  • Onset concentrated in adolescence.
  • Offending confined to a relatively short window; desistance typically occurs in early adulthood.
  • Behaviour often mirrors peer culture and situational opportunities rather than deep-seated deficits.
• Key explanatory concept: The Maturity Gap
  • Adolescents experience quasi-adult biological maturity without corresponding social privileges (e.g., autonomy, resources).
  • Observing LCP peers “breaking the rules” offers a template for gaining perceived adult status → imitation.
  • When legitimate adult roles (work, independence) become available, motivation to offend wanes → natural desistance.
• Practical takeaway: Most AL youths desist “on their own”; heavy criminal justice interventions may be unnecessary or counter-productive.

Visualising Trajectories (Hypothetical Graph)

• Moffitt’s schematic curve decomposes aggregate pattern into:
  • A flat, low-level curve (LCP) spanning childhood to adulthood.
  • A tall, narrow spike (AL) centred on mid-teens.
• Without disaggregation, the curves superimpose to create the canonical age–crime shape.

Refinements & Contemporary Evidence

• Subsequent longitudinal research suggests ≥ 1–2 additional trajectories (e.g., late-onset chronic, intermittent offenders).
• Nonetheless, the LCP vs. AL distinction remains useful for:
  • Understanding the bulk of age-related crime trends.
  • Targeting scarce resources (focus on high-harm, persistent minority).

Ethical & Policy Implications

• Recognising spontaneous desistance cautions against over-criminalising adolescents.
• Early identification of potential LCP individuals must balance prevention with risks of labelling and stigma.
• Data-driven allocation: intensive resources for persistent offenders; minimal intrusion for transient AL behaviour.

Key Numerical References & Formulas

• Age span of steep crime increase: $7\text{–}17$ years.
• Prevalence drop: $\text{By early 20s} \Rightarrow P \downarrow 50\%.$
• Aggregate desistance: $\text{Late 20s} \Rightarrow P \approx 0.$

Connections to Broader Criminological Theory

• Complements criminal careers literature on onset, persistence, and desistance.
• Aligns with developmental psychology (role of adolescence, neurodevelopment).
• Informs life-course criminology’s emphasis on turning points (education, work, marriage).

Study Tips

• Memorise definitions: Life-Course Persistent vs. Adolescent-Limited.
• Be able to sketch the age–crime curve and overlay the two trajectories.
• Understand the maturity gap and its role in AL offending.
• Review policy debates about intervention intensity across trajectories.
• Compare Moffitt’s taxonomy with alternative models (e.g., Sampson & Laub’s age-graded theory).