diff --git a/NAMESPACE b/NAMESPACE
index a77cff8..9d6723f 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,6 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
 export(action_disallow)
+export(cooldown)
 export(default_actions)
 export(last_rejected)
 export(last_rejected_permit)
@@ -14,4 +15,5 @@ importFrom(utils,packageName)
 importFrom(utils,packageVersion)
 importFrom(val.meter,class_metric_data_frame)
 importFrom(val.meter,class_package_matrix)
+importFrom(val.meter,metric_coerce)
 importFrom(val.meter,metrics)
diff --git a/R/available_packages.R b/R/available_packages.R
index 54c58d9..5dde5e8 100644
--- a/R/available_packages.R
+++ b/R/available_packages.R
@@ -41,7 +41,7 @@
 #' # attempt to install it
 #' install.packages(filtered_pkg)
 #' }
-#'
+#' @importFrom val.meter metric_coerce
 #' @export
 package_filter <- local({
   filter_id <- 0L
@@ -60,6 +60,8 @@ package_filter <- local({
     add = TRUE,
     envir = parent.frame()
   ) {
+    force(envir)
+
     metric_db <- db
     cond <- substitute(cond)
 
@@ -77,17 +79,28 @@ package_filter <- local({
       metric_defaults <- as.list(rep_len(NA, length.out = length(metrics())))
       names(metric_defaults) <- names(metrics())
 
-      # build our evaluation environemnt and evaluate filter expression
-      db <- db[!is.na(db[, "Package"]), ]
-      db <- as.data.frame(db)
-      met <- convert(class_package_matrix(metric_db), class_metric_data_frame)
-      met$Metric <- TRUE
-
-      db <- merge(db, met, by = c("Package", "Version", "MD5sum"), all = TRUE)
-      rownames(db) <- db[, "Package"]
+      if (!is.na(metric_db)) {
+        # build our evaluation environemnt and evaluate filter expression
+        db <- db[!is.na(db[, "Package"]), ]
+        db <- as.data.frame(db)
+        met <- convert(class_package_matrix(metric_db), class_metric_data_frame)
+        met$Metric <- TRUE
+
+        db <- merge(db, met, by = c("Package", "Version", "MD5sum"), all = TRUE)
+        rownames(db) <- db[, "Package"]
+        defaults <- metric_defaults()
+      } else {
+        defaults <- NA
+        db <- as.data.frame(db)
+      }
 
       # evaluate filter
-      envir <- build_filter_envir(values = db, envir = envir)
+      envir <- build_filter_envir(
+        values = db,
+        envir = envir,
+        defaults = defaults
+      )
+
       db$Include <- eval(cond, envir = envir)
       db$Exception[db$Package %in% exceptions] <- "allow list"
 
@@ -124,10 +137,17 @@ build_filter_envir <- function(
   defaults = metric_defaults(),
   envir = parent.frame()
 ) {
-  defaults_envir <- with(defaults, environment())
-  parent.env(defaults_envir) <- envir
+  if (is.matrix(values)) {
+    values <- as.data.frame(values)
+  }
   value_envir <- with(values, environment())
-  parent.env(value_envir) <- defaults_envir
+  if (!is.na(defaults)) {
+    defaults_envir <- with(defaults, environment())
+    parent.env(defaults_envir) <- envir
+    parent.env(value_envir) <- defaults_envir
+  }  else {
+    parent.env(value_envir) <- envir
+  }
   value_envir
 }
 
@@ -178,7 +198,14 @@ available_metric_fields <- function(repos = getOption("repos")) {
 
 #' @importFrom val.meter class_package_matrix class_metric_data_frame
 available_metrics <- function(repos = opt("repos")) {
+  if (!length(repos)) {
+    return(NA_character_)
+  }
+
   is_metric_db <- vlapply(repos, repo_is_metric_db)
+  if (!length(is_metric_db)) {
+    return(NA_character_)
+  }
   db <- available.packages(
     repos = repos[is_metric_db],
     fields = available_metric_fields(repos = repos),
@@ -188,3 +215,5 @@ available_metrics <- function(repos = opt("repos")) {
   # drop rows with missing Package field (used to drop `Format: ` header)
   db[!is.na(db[, "Package"]), ]
 }
+
+
diff --git a/R/filter_cooldown.R b/R/filter_cooldown.R
new file mode 100644
index 0000000..836cf65
--- /dev/null
+++ b/R/filter_cooldown.R
@@ -0,0 +1,31 @@
+#' Filter by date
+#'
+#' Implement a cooldown filter so that only packages that are older than a given
+#' threshold are installed.
+#'
+#' This helps to prevent installing packages recently published with a bug or an
+#' infiltration. For the same reason it prevents installing updates and patches
+#' of recently fixed packages.
+#'
+#' @param accepted A date of some time in the past until which published
+#'   packages are accepted.
+#' @param ... Other arguments passed to [`package_filter`].
+#'
+#' @returns A [`package_filter`]
+#'
+#' @examples
+#' # entire available packages set
+#' ap_complete <- available.packages()
+#' nrow(ap_complete)
+#'
+#' # available packages with cooldown filter applied
+#' ap <- available.packages(fields = "Published", filters = cooldown())
+#' ap <- subset(as.data.frame(ap), as.logical(Include))
+#' nrow(ap)
+#'
+#' @export
+cooldown <- function(accepted = Sys.Date() - 2 * 7, ...) {
+  stopifnot(is(accepted, "Date"))
+  stopifnot(accepted < Sys.Date())
+  package_filter(as.Date(Published) <= accepted, ...)
+}
diff --git a/man/cooldown.Rd b/man/cooldown.Rd
new file mode 100644
index 0000000..c95f21c
--- /dev/null
+++ b/man/cooldown.Rd
@@ -0,0 +1,37 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/filter_cooldown.R
+\name{cooldown}
+\alias{cooldown}
+\title{Filter by date}
+\usage{
+cooldown(accepted = Sys.Date() - 2 * 7, ...)
+}
+\arguments{
+\item{accepted}{A date of some time in the past until which published
+packages are accepted.}
+
+\item{...}{Other arguments passed to \code{\link{package_filter}}.}
+}
+\value{
+A \code{\link{package_filter}}
+}
+\description{
+Implement a cooldown filter so that only packages that are older than a given
+threshold are installed.
+}
+\details{
+This helps to prevent installing packages recently published with a bug or an
+infiltration. For the same reason it prevents installing updates and patches
+of recently fixed packages.
+}
+\examples{
+# entire available packages set
+ap_complete <- available.packages()
+nrow(ap_complete)
+
+# available packages with cooldown filter applied
+ap <- available.packages(fields = "Published", filters = cooldown())
+ap <- subset(as.data.frame(ap), as.logical(Include))
+nrow(ap)
+
+}
diff --git a/man/package_filter.Rd b/man/package_filter.Rd
index fa486cc..d9d2103 100644
--- a/man/package_filter.Rd
+++ b/man/package_filter.Rd
@@ -64,5 +64,4 @@ filtered_pkg <- pkgs[pkgs$Repository == "<filtered>", ][[1L]]
 # attempt to install it
 install.packages(filtered_pkg)
 }
-
 }
diff --git a/pkgdown/_pkgdown.yml b/pkgdown/_pkgdown.yml
index ddc13c2..676d6c3 100644
--- a/pkgdown/_pkgdown.yml
+++ b/pkgdown/_pkgdown.yml
@@ -66,6 +66,13 @@ reference:
   - contents:
       - package_filter
 
+  - title: >
+      Available filters
+    desc: >
+      A selection of ready-made filters
+  - contents:
+      - cooldown
+
   - title: >
       Actions
     desc: >