diff --git a/gtsam/geometry/Point2.h b/gtsam/geometry/Point2.h
index a99da460b..af5b1fbcd 100644
--- a/gtsam/geometry/Point2.h
+++ b/gtsam/geometry/Point2.h
@@ -58,7 +58,12 @@ public:
 	/// @{
 
 	/// construct from 2D vector
-	Point2(const Vector& v) : x_(v(0)), y_(v(1)) { assert(v.size() == 2); }
+	Point2(const Vector& v) {
+		if(v.size() != 2)
+			throw std::invalid_argument("Point2 constructor from Vector requires that the Vector have dimension 2");
+		x_ = v(0);
+		y_ = v(1);
+	}
 
   /// @}
   /// @name Testable
diff --git a/gtsam/geometry/Point3.h b/gtsam/geometry/Point3.h
index 4d15b65f5..3e7423c0a 100644
--- a/gtsam/geometry/Point3.h
+++ b/gtsam/geometry/Point3.h
@@ -48,21 +48,24 @@ namespace gtsam {
     /// @name Standard Constructors
   	/// @{
 
-    ///TODO: comment
+    /// Default constructor creates a zero-Point3
     Point3(): x_(0), y_(0), z_(0) {}
 
-    ///TODO: comment
-    Point3(const Point3 &p) : x_(p.x_), y_(p.y_), z_(p.z_) {}
-
-    ///TODO: comment
+    /// Construct from x, y, and z coordinates
     Point3(double x, double y, double z): x_(x), y_(y), z_(z) {}
 
   	/// @}
   	/// @name Advanced Constructors
   	/// @{
 
-    ///TODO: comment
-    Point3(const Vector& v) : x_(v(0)), y_(v(1)), z_(v(2)) {}
+    /// Construct from 3-element vector
+    Point3(const Vector& v) {
+			if(v.size() != 3)
+				throw std::invalid_argument("Point3 constructor from Vector requires that the Vector have dimension 3");
+			x_ = v(0);
+			y_ = v(1);
+			z_ = v(2);
+		}
 
     /// @}
     /// @name Testable