diff --git a/side-switch/side_switch.cpp b/side-switch/side_switch.cpp
index 2de3933..fb558c4 100644
--- a/side-switch/side_switch.cpp
+++ b/side-switch/side_switch.cpp
@@ -1,12 +1,138 @@
 #include "side_switch.hpp"
 
+#include "utils.hpp"
+
 #include <phosphor-logging/lg2.hpp>
+#include <sdbusplus/bus.hpp>
+
+#include <exception>
+#include <string>
+#include <variant>
+#include <vector>
 
 PHOSPHOR_LOG2_USING;
 
+bool sideSwitchNeeded()
+{
+    auto bus = sdbusplus::bus::new_default();
+    std::string fwRunningVersionPath;
+    uint8_t fwRunningPriority = 0;
+
+    // Get active image
+    try
+    {
+        std::vector<std::string> paths =
+            utils::getProperty<std::vector<std::string>>(
+                bus, "/xyz/openbmc_project/software/functional",
+                "xyz.openbmc_project.Association", "endpoints");
+        if (paths.size() != 1)
+        {
+            info("side-switch only supports BMC-purpose image systems");
+            return (false);
+        }
+        fwRunningVersionPath = paths[0];
+        info("Running firmware version path is {FW_PATH}", "FW_PATH",
+             fwRunningVersionPath);
+    }
+    catch (const std::exception& e)
+    {
+        error("failed to retrieve active firmware version: {ERROR}", "ERROR",
+              e);
+        return (false);
+    }
+
+    // Check if active image has highest priority (0)
+    try
+    {
+        fwRunningPriority = utils::getProperty<uint8_t>(
+            bus, fwRunningVersionPath.c_str(),
+            "xyz.openbmc_project.Software.RedundancyPriority", "Priority");
+        info("Running firmware version priority is {FW_PRIORITY}",
+             "FW_PRIORITY", fwRunningPriority);
+    }
+    catch (const std::exception& e)
+    {
+        error("failed to read priority from active image: {ERROR}", "ERROR", e);
+        return (false);
+    }
+
+    // If running at highest priority (0) then no side switch needed
+    if (fwRunningPriority == 0)
+    {
+        info("Running image is at priority 0, no side switch needed");
+        return (false);
+    }
+
+    // Need to check if any other BMC images on system have a higher priority
+    std::vector<std::string> allSoftwarePaths;
+    try
+    {
+        auto method = bus.new_method_call("xyz.openbmc_project.ObjectMapper",
+                                          "/xyz/openbmc_project/object_mapper",
+                                          "xyz.openbmc_project.ObjectMapper",
+                                          "GetSubTreePaths");
+        method.append("/xyz/openbmc_project/software");
+        method.append(0); // Depth 0 to search all
+        method.append(
+            std::vector<std::string>({"xyz.openbmc_project.Software.Version"}));
+        auto reply = bus.call(method);
+        reply.read(allSoftwarePaths);
+        if (allSoftwarePaths.size() <= 1)
+        {
+            info("only 1 image present in flash so no side switch needed");
+            return (false);
+        }
+    }
+    catch (const std::exception& e)
+    {
+        error("failed to retrieve all firmware versions: {ERROR}", "ERROR", e);
+        return (false);
+    }
+
+    // Cycle through all firmware images looking for a BMC version that
+    // has a higher priority then our running image
+    for (auto& fwPath : allSoftwarePaths)
+    {
+        if (fwPath == fwRunningVersionPath)
+        {
+            info("{FW_PATH} is the running image, skip", "FW_PATH", fwPath);
+            continue;
+        }
+        try
+        {
+            uint8_t thisPathPri = utils::getProperty<uint8_t>(
+                bus, fwPath.c_str(),
+                "xyz.openbmc_project.Software.RedundancyPriority", "Priority");
+
+            if (thisPathPri < fwRunningPriority)
+            {
+                info(
+                    "{FW_PATH} has a higher priority, {FW_PRIORITY}, then running priority",
+                    "FW_PATH", fwPath, "FW_PRIORITY", thisPathPri);
+                return (true);
+            }
+        }
+        catch (const std::exception& e)
+        {
+            // This could just be a host firmware image, just keep going
+            info("failed to read a BMC priority from {FW_PATH}: {ERROR}",
+                 "FW_PATH", fwPath, "ERROR", e);
+            continue;
+        }
+    }
+
+    return (false);
+}
+
 int main()
 {
     info("Checking for side switch reboot");
 
-    // TODO - Future commits in series to fill in logic
+    if (!sideSwitchNeeded())
+    {
+        info("Side switch not needed");
+        return 0;
+    }
+
+    // TODO - Future commits in series to fill in rest of logic
 }