Family background: the dynasty of Stoic opposition. Rusticus belonged to a family that had been part of the "Stoic opposition" of the first century — the line of Roman senator-Stoics who voiced moral criticism of the principate from Nero through Domitian. His grandfather is Q. Junius Arulenus Rusticus, friend and follower of Thrasea Paetus; tribune of the plebs in 66, praetor in 69, suffect consul about 92; he wrote a laudatory life of Thrasea (and, on some testimonies, of Helvidius Priscus too), for which Domitian executed him in 93 in the course of the repressions against the philosophers (the expulsion of the philosophers from Rome, the execution of Arulenus, Herennius Senecio, the exile of Epictetus). This line — Thrasea Paetus → Helvidius Priscus → Arulenus Rusticus → Herennius Senecio — was the canonical Stoic martyrology by the beginning of the second century (see Tac. Agr. 2; Hist. 4.5–8).

Junius Rusticus the philosopher thus inherited the direct Stoic tradition of resistance and the canonical texts of this line (including the Vita Thraseae and the Vita Helvidii). Under Antoninus Pius and Marcus the family was rehabilitated, and Rusticus-the-grandson came to a standing far surpassing what his grandfather had not been allowed to attain.

Career under the Antonines. Rusticus's senatorial career can be reconstructed only in general outline. Two peaks are secure:

• Ordinary consul of 162 — jointly with Lucius Verus (in the first year of the joint reign of Marcus and Verus, after the death of Antoninus Pius in 161). To be ordinary consul in the year in which the consular colleague is the co-emperor is the highest mark of political favour.
• Praefectus urbi under Marcus, holding the office apparently for a considerable period (on one reconstruction from 162 almost to the end of the 160s). The city prefecture is the highest urban magistracy, the chair of the senatorial court, effectively the head of the Roman capital's administration.

Marcus and Rusticus: a long relationship. Rusticus's tutelage over Marcus, which probably began in Marcus's adolescent and young-adult years (the mid-to-late 130s), did not break off with Marcus's accession. Dio Cassius (71.35) specifically observes that Marcus as emperor regularly consulted Rusticus on matters of state, embraced him publicly at meetings, and at his death asked the senate for a decree of statues in his honour. This is a continuing presence: not a teacher of youth, but the permanent counsellor of the ruler.

Rusticus and the trial of Justin Martyr. Around 165 (the precise dating is disputed, the range is c. 162–168) the prefect of the city, Rusticus (identified with Junius Rusticus), presided over the trial of Justin Martyr — the Christian apologist, author of the first and second Apologies, addressed to Antoninus Pius and Marcus respectively — and condemned Justin and his disciples to death for the confession of Christianity. The Acta Iustini (the martyrological acts) preserve the protocol of this trial. The episode is historically weighty and philosophically uncomfortable: the principal Stoic teacher of the "philosopher on the throne" Marcus turned out to be the magistrate who executed the founding figure of second-century philosophical Christianity. In the Meditations Marcus mentions the Christians only once (Med. 11.3) — and with manifest incomprehension.

• 01-07 — the principal, developed portrait; the longest after 01-16 (Antoninus Pius) and 01-17 (the thanksgiving to the gods).
• 01-17 — the thanksgiving to the gods for "having received good teachers"; Rusticus implicitly among them.
• Indirectly — Med. 1.17 — gratitude for the meeting with the right philosophical company.

• SHA Marcus 3.3 — Rusticus among the principal philosophical teachers of Marcus; 11.3 — his consulate of 162 and his prefecture.
• Dio Cassius 71.35 — the continuation of the teacher-counsellor relationship of Rusticus and the emperor Marcus; the detail of the public embraces.
• Tacitus, Agricola 2; Historiae 4.5–8 — the related Stoic martyrological line (Thrasea Paetus, Helvidius Priscus, Arulenus Rusticus).
• Acta Iustini (Acts of the Christian Martyrs, ed. Musurillo) — the protocol of the trial of Justin Martyr and his disciples under the presidency of the prefect Rusticus.
• PIR² I 815 — the standard prosopographical entry.
• A. Birley, Marcus Aurelius: A Biography, rev. ed., Routledge, 2000, ch. 3 ("Education") and passim — the reconstruction of Rusticus's role, of his political career, and of his relations with the emperor Marcus.
• A. S. L. Farquharson, The Meditations of the Emperor Marcus Antoninus, Oxford 1944, vol. II, ad 1.7 — the standard philological commentary on Med. 1.7.
• R. Hard, Marcus Aurelius: Meditations, OWC, Oxford 2011, notes ad 1.7.
• P. Hadot, The Inner Citadel, tr. M. Chase, Harvard 1998, especially ch. 3 ("The Discourses of Epictetus") — the analysis of the role of the Epictetan Discourses in the formation of Marcus and of the significance of the transmission through Rusticus.
• M. Griffin, "Iure plectimur: The Roman Critique of Roman Imperialism," PCPS 28 (1982) — an analysis of the first-century Stoic opposition as context for the inheritance of Rusticus.
• C. Edwards & G. Woolf (eds.), Rome the Cosmopolis, Cambridge 2003 — the context of the philosophical circles of the second century.