Let $a,$ $b,$ and $c$ be distinct real numbers.  Find the degree of the polynomial
\[p(x) = \frac{(x - b)(x - c)}{(a - b)(a - c)} + \frac{(x - a)(x - c)}{(b - a)(b - c)} + \frac{(x - a)(x - b)}{(c - a)(c - b)}.\]
Note that $p(x)$ has degree at most 2.  Also, $p(a) = p(b) = p(c) = 1.$  Thus, the polynomials $p(x)$ and 1 agree at three different values, so by the Identity Theorem, they are the same polynomial.  Hence, the degree of $p(x)$ (which is the constant polynomial 1) is $\boxed{0}.$

You can check manually that
\[p(x) = \frac{(x - b)(x - c)}{(a - b)(a - c)} + \frac{(x - a)(x - c)}{(b - a)(b - c)} + \frac{(x - a)(x - b)}{(c - a)(c - b)}\]simplifies to 1.