  This paper presents an alternative approach to controlled surgery
obstructions. The obstruction for a degree one normal map $(f,b): M^n
\rightarrow X^n$ with control map $q: X^n \rightarrow B$ to complete controlled
surgery is an element $\sigma^c (f, b) \in H_n (B, \mathbb{L})$, where $M^n,
X^n$ are topological manifolds of dimension $n \geq 5$. Our proof uses
essentially the geometrically defined $\mathbb{L}$-spectrum as described by
Nicas (going back to Quinn) and some well known homotopy theory. We also
outline the construction of the algebraically defined obstruction, and we
explicitly describe the assembly map $H_n (B, \mathbb{L}) \rightarrow L_n
(\pi_1 (B))$ in terms of forms in the case $n \equiv 0 (4)$. Finally, we
explicitly determine the canonical map $H_n (B, \mathbb{L}) \rightarrow H_n (B,
L_0)$.
