LEGO’s modern interlocking brick design was patented in 1958.
The crucial patent covered the tube-and-stud coupling system that lets bricks connect securely while remaining easy to separate. The design was filed by The LEGO Group on 28 January 1958, the same day that company founder Ole Kirk Christiansen died.
Earlier LEGO plastic bricks had already been sold, beginning with Automatic Binding Bricks in 1949, but the 1958 design significantly improved clutch power and stability. This distinction matters: 1949 marks the early plastic-brick era, while 1958 marks the modern basic brick design.
Although the original patent has expired, LEGO-compatible bricks can still be made by other companies because the basic shape is no longer protected by that patent. LEGO continues to protect its brand and individual product features through other forms of intellectual property.