Sir James Altham (died 1617) was an English judge.
Altham was descended from Christopher Altham of Girlington, in the West Riding of Yorkshire. He was the third son of James Altham of Mark Hall, Latton, in Essex, Sheriff of London in 1557-58, and sheriff of Essex in 1570, by Elizabeth Blancke, daughter of Thomas Blancke of London, Haberdasher, and sister of Sir Thomas Blanke, who was Lord Mayor of London in 1583. Altham was educated at Trinity College, Cambridge, entered Gray's Inn in 1575 and was called to the bar in 1581.
He is mentioned in Croke's reports for the first time as arguing a case in the Queen's Bench in 1587. In 1589 he was elected M.P. for Bramber in Sussex. He was knighted in 1605.
He was appointed reader at Gray's Inn in 1600, and in 1603 double reader (duplex lector). In the same year he was made serjeant-at-law. In 1606 he was appointed one of the barons of the exchequer, in succession to Sir J. Savile, and knighted. In 1610, a question having arisen concerning the power of the crown to impose restrictions on trade and industry by proclamation, the two chief justices, the chief baron, and Baron Altham were appointed to consider the matter. The result of their consultation was that they unanimously resolved "that the king by his proclamation cannot create any offence which was not an offence before ... That the king hath no prerogative but that which the law of the land allows him ... and lastly, that if an offence be not punishable in the Star Chamber, the prohibition of it by proclamation cannot make it punishable there."’
Altham was one of the judges whose opinion was taken in 1611 by Lord Chancellor Ellesmere on the case of the heretics Bartholomew Legate and Edward Wightman, whom Archbishop Abbot wanted burned. Altham was reputed hostile to Edward Coke, who was deliberately not consulted. The two men were burned, one at Smithfield, the other at Burton-upon-Trent.