He married Isabella Law, daughter of William Law, Esq. of Elvingston, East-Lothian. The third son—the subject of our sketch—was born in 1741. His elder brothers were destined to mercantile pursuits, but Robert was educated for the legal profession. He commenced his studies at the High School of Edinburgh, and from thence was transferred to the University, where he formed friendships which subsequently materially aided him in his progress through life. In particular he commenced an intimacy with Henry Dundas, afterwards Lord Melville, which only terminated with their lives. Mr. Blair was a year younger than his friend Lord Melville. The latter was admitted a member of the Faculty of Advocates in 1763, and the former the following year.

This adoption of a profession, in which so many fail of success, was considered at least a bold, if not an inconsiderate choice, by a young man without fortune; but the extended practice, which his talents almost instantaneously commanded, dispelled the apprehensions of his friends. Blair rapidly rose to eminence as a lawyer; and in most cases of importance was retained as a leading counsel. The celebrated Henry Erskine and he were generally pitted against each other, as the two most eloquent as well as able members of the bar. However much Erskine might surpass his opponent in witty observation, or ingenious remark, Blair was infinitely his superior as a clear reasoner and sound lawyer.

Mr. Blair was for several years one of the Assessors of the city of Edinburgh, and an Advocate-depute. In 1789, he was appointed Solicitor-General for Scotland; and, in 1801, was unanimously elected Dean of the Faculty of Advocates. His election of Dean was without a single dissentient voice, save that of Mr. Wilde, who cried out —

"Harry Erskine for ever!" When the intelligence was communicated to Mr. Blair, his own words were—"Nothing gives me more pleasure than the fact, that those opposed to me in politics were the first to vote in my favour."

On the change of Ministry which took place in 1806, Mr Blair was removed from the solicitorship; on which event he received a polite apology from the new minister, stating the necessity he was under of promoting his own party. This communication—no doubt dictated by good feeling—was perfectly unnecessary, in so far as the feelings of the ex-solicitor were concerned. Then, as now, a change in the Crown officers invariably succeeded a change in the Cabinet. The friends of either party were therefore prepared to rise or fall as the scale preponderated. Far from being out of temper with this turn of the political wheel, Mr. Blair showed his magnanimity, by proffering to his successor—John Clerk, afterwards Lord Eldin—the use of his gown, until the latter should get one prepared for himself. On the return of his friends to power next year, Mr. Blair was offered the restoration of his former honour; but he declined not only this, but also the higher office of Lord Advocate. In 1808, on the resignation of Sir Ilay Campbell, he was raised to the Presidency of the College of Justice—a choice which gave satisfaction to all parties.

During the short period that his lordship discharged the duties of this high trust, his conduct as a judge realised the expectations formed from a knowledge of his abilities at the bar. In his character were not only blended those native qualities of mind, which, aided by the acquirements of study, combine to constitute superior talent, but he brought with him to the bench that "innate love of justice and abhorrence of iniquity, without which, as he himself emphatically declared, when he took the chair of the Court, all other qualities avail nothing, or rather are worse than nothing."

In Peter's Letters to his Kinsfolk the character of the Lord President is thus sketched:—"It would appear as if the whole of his clear and commanding intellect had been framed and tempered in such a way as to qualify him peculiarly and expressly for being, what the Stagyrite has finely called, ' a living equity '—one of the happiest, and perhaps one of the rarest, of all the combinations of mental powers. By all men of all parties the merits of this great man also were alike acknowledged; and his memory is at this moment alike held in reverence by them all. Even the keenest of his now surviving political opponents [the late Lord Eldin] —himself one of the greatest lawyers that Scotland ever has produced—is said to have contemplated the superior intellect of Blair with a feeling of respectfulness not much akin to the common cast of his disposition. After hearing the President overturn, without an effort, in the course of a few clear and short sentences, a whole mass of ingenious sophistry, which it had cost himself much labour to erect, and which appeared to be regarded as insurmountable by all the rest of his audience, this great barrister is said to have sat for a few seconds ruminating with much bitterness on the discomfiture of his cause, and then to have muttered between his teeth—'My man! God Almighty spared nae lyains when He made your trains!'' Those that have seen Mr. Clerk, and know his peculiarities, appreciate the value of this compliment, and do not think the less of it because of its coarseness."

The Lord President did not long enjoy that dignity which he gave such promise of rendering equally honourable to himself and beneficial to his country. He died suddenly on the 20th May, 1811, aged sixty-eight; and it is not a little remarkable that the very same week terminated the life of his early and steady friend Lord Melville, who, as has been elsewhere mentioned, had come to Edinburgh to the President's funeral. The death of these two very eminent men, as it were by one blow, was looked upon as a national calamity. Their early friendship—their dying almost at the same period—and the high and important stations which they had occupied as public men, naturally created a more than ordinary interest on the occasion of their demise. Their houses being next to one another, with only a single wall between the bedrooms where the dead bodies of each were lying at the same time, made a deep impression on their friends. In a Monody, by an anonymous author, who has drawn the characters of Lord Melville and President Blair with tolerable ability, their friendship and death are thus alluded to:—

"Two mighty oaks that, side by side,
For ages towered, the forest's pride,
And nourished in their shade,
Sapling and tree, and waving wood;
On whose broad breast October's flood,
And winter's war, and whirlwind rude,
Their baffled might essayed.

"Their musty boughs, compact on high,
Seasons with all their storms defy—
While some scant brook that oozes by.
Unheeded and unknown,
Slow on each hidden fibre preys—
Loosens amain the earth-fast base;
And far the forest wonder lays,
A thundering ruin prone!

"Thus, thus, lamented chiefs! ye fell
From glory's loftiest pinnacle,
By destiny severe:
Ere, tranced in sorrow, we had paid
Due rites to Blair's illustrious shade.
With heart-struck woe we hung dismay'd
O'er Melville's honoured bier."

The volume from which the above lines are taken, published in 4to at 4s., is entitled "Monody on the Death of the Right Hon. Henry Lord Viscount Melville, and of the Right Hon. Robert Blair of Avontoun, Lord President of the College of Justice." Edinburgh, 1811.

As a memorial of respect to his high talents, and to mark the estimation in which he was held, a statue of the Lord President Blair, by Chantry, is placed in the First Division of the Inner House of the Court of Session.

Mr. Blair married Isabella Cornelia Halkett, youngest daughter of Colonel Charles Craigie Halkett of Lawhill, Fifeshire, who still survives. He left one son and three daughters—one of whom is the wife of Alexander Maconochie, Lord Meadowbank, one of the Senators of the College of Justice, and a Lord of Justiciary.