diff --git a/src/bin/topola-sdl2-demo/main.rs b/src/bin/topola-sdl2-demo/main.rs
index 12cf93c..f36e54a 100644
--- a/src/bin/topola-sdl2-demo/main.rs
+++ b/src/bin/topola-sdl2-demo/main.rs
@@ -61,7 +61,7 @@ impl RulesTrait for SimpleRules {
             .unwrap_or(&10.0)
     }
 
-    fn clearance_net_limit(&self, net: i64) -> f64 {
+    fn largest_clearance(&self, net: i64) -> f64 {
         let mut highest_clearance = 0.0;
 
         for ((net1, net2), clearance) in self.net_clearances.iter() {
diff --git a/src/dsn/design.rs b/src/dsn/design.rs
index df90382..55b63e1 100644
--- a/src/dsn/design.rs
+++ b/src/dsn/design.rs
@@ -8,41 +8,38 @@ use crate::{
 use super::{
     de::{from_str, Error},
     structure::Pcb,
+    rules::Rules,
 };
 
 #[derive(Debug)]
 pub struct DsnDesign {
     pcb: Pcb,
+    rules: Rules,
 }
 
 impl DsnDesign {
     pub fn load_from_file(filename: &str) -> Result<Self, Error> {
         let contents = std::fs::read_to_string(filename).unwrap(); // TODO: remove unwrap.
+        let pcb = from_str::<Pcb>(&contents)?;
+
+        let rules = Rules::from_pcb(&pcb);
 
         Ok(Self {
-            pcb: from_str::<Pcb>(&contents)?,
+            pcb,
+            rules,
         })
     }
 
-    pub fn make_layout(&self) -> Layout<&Pcb> {
-        let mut layout = Layout::new(&self.pcb);
-
-        // this holds the mapping of net names to numerical IDs (here for now)
-        let net_ids: HashMap<String, usize> = HashMap::from_iter(
-            self.pcb.network.classes[0]
-                .nets
-                .iter()
-                .enumerate()
-                .map(|(id, net)| (net.clone(), id)),
-        );
+    pub fn make_layout(&self) -> Layout<&Rules> {
+        let mut layout = Layout::new(&self.rules);
 
         // mapping of pin id -> net id prepared for adding pins
         let pin_nets = if let Some(nets) = self.pcb.network.nets.as_ref() {
-            HashMap::<String, usize>::from_iter(
+            HashMap::<String, i64>::from_iter(
                 nets.iter()
                     .map(|net| {
                         // resolve the id so we don't work with strings
-                        let net_id = net_ids.get(&net.name).unwrap();
+                        let net_id = self.rules.net_ids.get(&net.name).unwrap();
 
                         // take the list of pins
                         // and for each pin id output (pin id, net id)
@@ -52,7 +49,7 @@ impl DsnDesign {
                     .flatten(),
             )
         } else {
-            HashMap::<String, usize>::new()
+            HashMap::<String, i64>::new()
         };
 
         // add pins from components
@@ -70,7 +67,7 @@ impl DsnDesign {
                 for pin in &image.pins {
                     let pin_name = format!("{}-{}", place.name, pin.id);
                     let net_id = pin_nets.get(&pin_name).unwrap();
-                    let continent = layout.add_continent(*net_id as i64);
+                    let continent = layout.add_continent(*net_id);
 
                     let padstack = &self
                         .pcb
@@ -102,8 +99,8 @@ impl DsnDesign {
             .vias
             .iter()
             .map(|via| {
-                let net_id = net_ids.get(&via.net.0).unwrap();
-                let continent = layout.add_continent(*net_id as i64);
+                let net_id = self.rules.net_ids.get(&via.net.0).unwrap();
+                let continent = layout.add_continent(*net_id);
 
                 // find the padstack referenced by this via placement
                 let padstack = &self
@@ -128,8 +125,8 @@ impl DsnDesign {
             .collect();
 
         for wire in self.pcb.wiring.wires.iter() {
-            let net_id = net_ids.get(&wire.net.0).unwrap();
-            let continent = layout.add_continent(*net_id as i64);
+            let net_id = self.rules.net_ids.get(&wire.net.0).unwrap();
+            let continent = layout.add_continent(*net_id);
 
             // add the first coordinate in the wire path as a dot and save its index
             let mut prev_index = layout
diff --git a/src/dsn/rules.rs b/src/dsn/rules.rs
index 5fcef0d..ef172f5 100644
--- a/src/dsn/rules.rs
+++ b/src/dsn/rules.rs
@@ -1,15 +1,97 @@
+use std::collections::HashMap;
+
 use crate::layout::rules::{Conditions, RulesTrait};
 
 use super::structure::Pcb;
 
-impl<'a> RulesTrait for &'a Pcb {
-    fn clearance(&self, _conditions1: &Conditions, _conditions2: &Conditions) -> f64 {
-        // Placeholder for now.
-        10.0
-    }
+#[derive(Debug)]
+pub struct Rule {
+    pub width: f64,
+    pub clearance: f64,
+}
 
-    fn clearance_net_limit(&self, _net: i64) -> f64 {
-        // Placeholder for now.
-        10.0
+impl Rule {
+    fn from_dsn(rule: &super::structure::Rule) -> Self {
+        Self {
+            width: rule.width.0 as f64 / 100.0,
+            clearance: rule.clearances[0].value as f64 / 100.0, // picks the generic clearance only for now
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Rules {
+    structure_rule: Rule,
+    // net class name -> rule
+    class_rules: HashMap<String, Rule>,
+
+    // net names -> net IDs for Layout
+    pub net_ids: HashMap<String, i64>,
+    // net ID -> net class
+    net_id_classes: HashMap<i64, String>,
+}
+
+impl Rules {
+    pub fn from_pcb(pcb: &Pcb) -> Self {
+        let net_ids = HashMap::from_iter(
+            pcb.network.classes[0]
+                .nets
+                .iter()
+                .enumerate()
+                .map(|(id, net)| (net.clone(), id as i64)),
+        );
+
+        let mut net_id_classes = HashMap::new();
+        let class_rules = HashMap::from_iter(
+            pcb.network.classes
+                .iter()
+                .inspect(|class| {
+                    for net in &class.nets {
+                        let net_id = net_ids.get(net).unwrap();
+                        net_id_classes.insert(*net_id, class.name.clone());
+                    }
+                })
+                .map(|class| (class.name.clone(), Rule::from_dsn(&class.rule)))
+        );
+
+        Self {
+            structure_rule: Rule::from_dsn(&pcb.structure.rule),
+            class_rules,
+            net_ids,
+            net_id_classes,
+        }
+    }
+
+    pub fn get_rule(&self, net: i64) -> &Rule {
+        if let Some(netclass) = self.net_id_classes.get(&net) {
+            self.class_rules.get(netclass).unwrap_or(&self.structure_rule)
+        } else {
+            &self.structure_rule
+        }
+    }
+}
+
+impl<'a> RulesTrait for &'a Rules {
+    fn clearance(&self, conditions1: &Conditions, conditions2: &Conditions) -> f64 {
+        let clr1 = self.get_rule(conditions1.net).clearance;
+        let clr2 = self.get_rule(conditions2.net).clearance;
+
+        if clr1 > clr2 {
+            clr1
+        } else {
+            clr2
+        }
+    }
+
+    fn largest_clearance(&self, _net: i64) -> f64 {
+        let mut largest: f64 = 0.0;
+
+        for (class, rule) in &self.class_rules {
+            if rule.clearance > largest {
+                largest = rule.clearance;
+            }
+        }
+
+        largest
     }
 }
diff --git a/src/layout/layout.rs b/src/layout/layout.rs
index 57e1184..75e9c73 100644
--- a/src/layout/layout.rs
+++ b/src/layout/layout.rs
@@ -796,7 +796,7 @@ impl<R: RulesTrait> Layout<R> {
         let limiting_shape = node
             .primitive(self)
             .shape()
-            .inflate(self.rules.clearance_net_limit(node.primitive(self).net()));
+            .inflate(self.rules.largest_clearance(node.primitive(self).net()));
         let mut inflated_shape = limiting_shape; // Unused temporary value just for initialization.
         let conditions = node.primitive(self).conditions();
 
diff --git a/src/layout/rules.rs b/src/layout/rules.rs
index b46dcbd..094fab0 100644
--- a/src/layout/rules.rs
+++ b/src/layout/rules.rs
@@ -16,5 +16,5 @@ pub struct Conditions {
 
 pub trait RulesTrait {
     fn clearance(&self, conditions1: &Conditions, conditions2: &Conditions) -> f64;
-    fn clearance_net_limit(&self, net: i64) -> f64;
+    fn largest_clearance(&self, net: i64) -> f64;
 }