Nearly eight years after the Minnesota Supreme Court ruled that anglers have the same privacy rights in an ice fishing shelter as they do in their homes, Minnesota's conservation officers play cat-and-mouse with some who use the ruling to fish illegally.

Before the 2002 decision, officers stepped into ice houses uninvited after knocking and announcing who they were. Anglers fishing with too many lines or keeping too many fish often were caught red-handed.

But the court ruling was a game-changer. Justices said officers need permission -- or a search warrant -- to enter an ice fishing house, the same as they would a home.

Most anglers still welcome officers inside their winter shelters, because most are abiding by the rules. But some agree to open their doors only after making officers wait a few moments -- possibly to hide illegal activity. It's uncertain how much of that takes place now or whether there are more violations occurring because of the court ruling.

Officers simply don't know what's going on behind closed doors. But they regularly encounter cases that underscore the problem:

Conservation officer Mike Martin of St. Cloud knocked on the door of the ice fishing house on Pleasant Lake recently. "Just a minute," he was told.

Two more knocks got the same response. Finally the angler let Martin inside. He was fishing with two lines -- the legal maximum -- but a rod rested near a third hole in the ice.

"I noticed it had no line through the eyes of the rod," Martin said. "Then I saw the line on the reel was pig-tailed. When someone burns their line with a cigarette, it curls up at the end like a pig's tail. I looked down the hole and saw fishing line."

Martin picked up the line and the lure attached to it.

"He shrugged his shoulders; he knew he was caught," Martin said.

The angler was cited for fishing with too many lines, which will cost him $123 in fines and court costs.

When anglers hesitate to open their doors, officers call it "being delayed," and they say it's fairly common.

"I would say I'm delayed entering a fish house every other day," Martin said. "I've never been told, 'Go away, I don't want to talk to you,' as some officers have.''

Martin said anglers fishing with too many lines simply pull the lines up or cut them before opening the door.

"It's relatively common. They delay us, then when they open the door, there'll be two lines down and another fishing pole sitting there with a minnow wiggling. There's not very much you can do."

Brice Vollbrecht, a conservation officer in Blackduck, was checking anglers on Upper Red Lake recently when he pulled up to a fish house on his snowmobile. Through a window, he saw the angler quickly moving from hole to hole inside.

"I knocked and he let me in right away," he said. "I asked him how many lines he was fishing with, and he said two." But then Vollbrecht noticed black braided line floating in two of the holes.

"I pulled them up and he admitted to cutting the lines before answering the door. He said fishing was slow, so he was trying more lines." Other anglers with too many lines claim they were just checking water depth or wanted to try different colored lures, Vollbrecht said. He said about one in 20 anglers he checks delay his admittance to their ice fishing shelters.

"It makes it a lot more difficult; they can hide so much stuff in a short time." But, he said, "I've never had anyone refuse to let me in." And anglers must show officers their fishing licenses, if asked.

About half the DNR's 140 field officers -- including Vollbrecht and Martin -- have been hired since the 2002 decision, said Jim Konrad, DNR enforcement chief. That means they never experienced the old method of walking in on anglers without permission. Konrad was a conservation officer patrolling the Lake Minnetonka area at the time.

"That [ruling] was very frustrating for many of us," Konrad said. "Afterwards, rarely a day went by where I wasn't denied access. People are getting away with violations who, in the past, we'd have the opportunity to catch."

But it's difficult to determine the ramifications of the ruling, he said. "Fishing citations have remained pretty stable, but angling has increased over the past seven years," he said. The DNR doesn't know if there's been a measurable effect on the fish population in lakes.

"It would be hard to quantify," Konrad said.

Konrad said he still disagrees with the ruling. "There was no expectation of privacy [in an ice shack]," he said. Anglers fish on public waters and participate in a highly regulated activity.

Scott Fritz was the conservation officer who cited an angler on Circle Lake near Faribault in 2001, which triggered the court case. The angler was cited for having three lines in the water and for having a small amount of marijuana. His attorney challenged the law, saying Fritz violated his constitutional right to privacy. The state Supreme Court eventually agreed.

"It's not for me to say if the decision was right or wrong, but I can understand how the ruling went the way it did," said Fritz, a 25-year DNR veteran who now patrols near La Crescent, Minn. "Once we started putting bunks and stoves and everything else [in an ice house], it wasn't just a shelter to get out of the wind and snow anymore. I understand how the court could determine they were temporary places of abode. But it definitely has been a hindrance for us.

"We're doing the best we can to enforce the laws. Is it adequate? That has yet to be determined."

dsmith@startribune.com